This slow cooker Mongolian beef with kimchi pairs tender beef in a sweet-savory soy and ginger sauce with tangy Korean fermented cabbage. Mongolian beef is a Chinese-American restaurant-style dish, despite its name, while kimchi has many Korean regional and family variations; this version brings the two together for a richly flavored, easy-to-serve meal.
Ingredients
- 2 lb (907 g) boneless beef chuck steak, trimmed and cut across the grain into strips about ½ inch (1.3 cm) thick
- ½ cup (120 ml) low-sodium soy sauce
- ½ cup (120 ml) low-sodium beef broth or water
- ⅓ cup (67 g) packed light brown sugar
- 1 tablespoon (15 ml) toasted sesame oil
- 4 garlic cloves (about 12 g), finely minced
- 1 tablespoon (6 g) finely grated fresh ginger
- 2 tablespoons (16 g) cornstarch, for coating the beef
- 1 tablespoon (8 g) cornstarch, for thickening the sauce
- 2 tablespoons (30 ml) cold water, for the thickening slurry
- 1 cup (150 g) napa cabbage kimchi, roughly chopped, plus 2 tablespoons (30 ml) kimchi juice
- 4 scallions (about 60 g), thinly sliced, with white and green parts separated
- ¼ teaspoon (0.5 g) red pepper flakes, optional
- 1 tablespoon (9 g) toasted sesame seeds, optional, for serving
Instructions
- Prepare the beef and sauce. Pat the thawed beef dry and slice it across the grain into evenly sized strips; cutting across the visible muscle fibers helps keep each bite easier to chew. Put the strips in a bowl, sprinkle over the 2 tablespoons of cornstarch, and toss until lightly coated. In a separate bowl, whisk together the soy sauce, broth, brown sugar, sesame oil, garlic, ginger, kimchi juice, and red pepper flakes if using. The sauce will taste salty and sweet before cooking, but the beef and kimchi will balance it as they cook.
- Load the slow cooker. Arrange the coated beef in the slow cooker and pour the sauce mixture over it. Stir gently so the strips are moistened and spread into a fairly even layer. Use thawed beef rather than frozen meat, and avoid filling the cooker beyond its recommended capacity. Cover with the lid; keeping the lid in place helps the cooker maintain a steady temperature.
- Cook until tender. Cook on LOW for 3 hours 30 minutes. Slow cookers vary, so use the time as a guide rather than a guarantee: the beef should be tender but still hold its shape. Do not judge doneness by color alone. Check a thick strip in the center with a food thermometer; USDA FSIS lists 145°F (63°C) with a 3-minute rest as the safe minimum for whole cuts of beef. If the beef has not reached that temperature, continue cooking and check again. The longer, gentle cooking in this recipe also helps chuck become tender.
- Add the kimchi and thicken. Stir the cold water into the remaining 1 tablespoon of cornstarch until smooth. Add the chopped kimchi and the slurry to the slow cooker, then stir carefully to distribute them without breaking up the beef. Cover and cook on LOW for 20 minutes, until the sauce is glossy and thickened and the kimchi is hot throughout. The cabbage is added near the end so it keeps some texture and its lively, fermented flavor.
- Rest and finish. Turn off the slow cooker and let the beef stand for 3 minutes to meet the USDA FSIS rest guidance for whole cuts. Taste the sauce and adjust only if needed; kimchi and soy sauce both contribute salt, while the brown sugar softens their sharp edges. Scatter the scallion whites and greens over the top, then add sesame seeds if desired. Serve while hot.
Tips
- Choose the right cut and slice it well. Chuck steak has enough connective tissue to turn tender during slow cooking and is usually more forgiving than a very lean cut. If you use flank steak instead, slice it thinly across the grain and begin checking earlier, since it can become dry or stringy if cooked too long. Keep the strips similar in thickness so they cook at a similar rate.
- Adjust the kimchi to your preference. Kimchi varies in saltiness, sourness, chili heat, and crunch. Start with a mild or medium napa cabbage kimchi if you want the Mongolian-style sauce to remain prominent. For a stronger fermented flavor, add a little more kimchi juice, but taste first because it can make the sauce saltier and more tart.
- Do not add extra liquid casually. The beef releases moisture as it cooks, and the slow cooker does not evaporate liquid as quickly as a skillet. The sauce may look thin before the cornstarch slurry goes in; give it the full finishing time before deciding it needs more thickener. If it is still looser than you like, mix another teaspoon of cornstarch with a teaspoon of cold water and stir it in, then cook for several minutes.
- Make the prep easier without compromising the result. You can slice the beef, mince the garlic, and grate the ginger the night before, storing them separately in covered containers in the refrigerator. Keep the beef chilled until it goes into the cooker, and wait to chop the kimchi if you want its smell to stay contained. Do not leave raw beef at room temperature while preparing the rest.
Serving Suggestions
Serve the beef and plenty of sauce over steamed short-grain or medium-grain rice. The rice catches the sweet, salty juices and gives the tangy kimchi room to stand out without making the meal feel too intense. For six portions, cook about 2 cups (370 g) uncooked rice according to its package directions; it will yield enough to serve alongside the beef. Rice is not included in the ingredient list because it is an accompaniment rather than part of the slow-cooker dish.
For a lighter-feeling plate, use a smaller scoop of rice and add steamed broccoli, sautéed bok choy, or quickly blanched green beans. Their mild flavor works well with the sauce. You can also serve the beef in lettuce cups, spooning a little sauce over each portion and adding extra kimchi or sliced scallions at the table. If serving guests, put additional kimchi on the side rather than stirring it all into the pot; different batches can vary considerably in heat and acidity.
Variations
Make it less sweet: Reduce the brown sugar to ¼ cup (50 g). The sauce will taste more savory and the kimchi’s tartness will be more noticeable. If you want a little more balance without restoring all the sweetness, add a teaspoon of sugar at the end, taste, and repeat only if needed.
Use a practical soy substitute: For a gluten-free version, choose certified gluten-free tamari in place of the soy sauce, checking the label on the kimchi and broth as well. Tamari is often a little rounder and less sharp in flavor, so the finished sauce may taste slightly different. Coconut aminos can also replace soy sauce, but they are generally sweeter and less salty; reduce the brown sugar and season cautiously after cooking.
Change the kimchi: Napa cabbage kimchi is the classic choice here, but a mild radish kimchi can give the dish a crisper bite and a more peppery, fresh character. If you cannot find kimchi, use 1 cup (150 g) drained sauerkraut and a pinch of chili flakes. That substitution brings acidity and crunch but lacks kimchi’s garlic, ginger, and Korean chili flavor, so add a small extra pinch of ginger and taste before serving.
Add vegetables: Stir sliced bell pepper into the slow cooker during the final 20 minutes if you like it tender but not collapsed. For firmer vegetables, steam them separately and serve alongside. Avoid adding delicate greens at the beginning; hours of slow cooking can make them overly soft and dilute the texture of the sauce.
Storage and Reheating
Refrigerate leftovers within 2 hours of cooking, transferring them to shallow, covered containers so they cool promptly. Store the beef with its sauce for 3–4 days in the refrigerator. The sauce may thicken as it chills, and the kimchi flavor can become more pronounced overnight. For longer storage, freeze portions in airtight, freezer-safe containers for up to 3 months for best quality. Thaw frozen portions in the refrigerator rather than on the counter.
Reheat only the amount you plan to eat. Warm it gently in a covered saucepan over medium-low heat, stirring occasionally and adding a splash of water or broth if the sauce is too thick. You can also use a microwave-safe covered dish, stirring partway through so the center heats evenly. USDA FSIS recommends reheating leftovers to 165°F (74°C); check the center with a food thermometer. Avoid repeatedly cooling and reheating the whole batch, which can affect both quality and safe handling.
Frequently Asked Questions
Is Mongolian beef actually from Mongolia?
Mongolian beef, as commonly served in North American Chinese restaurants, is a Chinese-American restaurant-style dish; its name does not mean that this preparation is a traditional dish from Mongolia. Recipes vary, but many use sliced beef with a sweet-savory soy-based sauce. This version adds kimchi, a Korean fermented vegetable preparation, for acidity, heat, and texture.
Will the kimchi make the whole dish very spicy?
Not necessarily. Kimchi heat depends on the brand or recipe, and the sauce’s brown sugar and beef mellow its sharpness. Choose mild kimchi and leave out the optional red pepper flakes for a gentler result. You can always serve extra kimchi or chili flakes at the table, where each person can adjust their portion.
Can I put frozen beef straight into the slow cooker?
No. Thaw the beef in the refrigerator before cooking it in the slow cooker. Frozen meat can spend too long warming through, so it may not heat safely and evenly. Keep raw beef refrigerated while you prepare the sauce, and wash hands, boards, and utensils that have touched it before using them for ready-to-eat food.
Can I cook this on HIGH instead of LOW?
LOW is preferable for chuck because gradual cooking helps it soften without forcing you to guess whether the strips are tender. Slow cookers differ, and a high setting can make thin beef strips overcook before the connective tissue in thicker pieces has softened. If you need to use HIGH, follow your appliance’s guidance, start checking well before the end, and use a thermometer as well as a tenderness check.
Why is my sauce thin, and can I fix it?
The sauce is naturally looser during most of the slow-cooking period, and the beef releases liquid as it cooks. Add the measured cornstarch slurry with the kimchi during the final 20 minutes and keep the lid on while it thickens. If it remains thin, stir in a small additional slurry made with cold water; never sprinkle dry cornstarch directly into the hot sauce, because it can form lumps.
Can I prepare the entire recipe ahead?
You can measure the sauce ingredients and prepare the beef the day before, but refrigerate the beef and sauce separately and do not leave them at room temperature. For the best texture, assemble and start the slow cooker when you are ready to cook. The finished dish also makes a useful make-ahead meal: refrigerate it promptly, then reheat portions to 165°F (74°C) before serving.
More recipes to cook
Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
Spotted an error? Tell us and we will correct it (corrections policy).