Lomo saltado sauce is the savory, tangy pan sauce that brings together Peru’s famous stir-fry of beef, red onion, tomatoes, and fries. Soy sauce, vinegar, and a little beef stock make a quick sauce that coats the ingredients without drowning them; recipes vary, but this balanced version is easy to adjust.
Ingredients
- 2 tablespoons (30 ml) soy sauce
- 2 tablespoons (30 ml) red wine vinegar
- ¼ cup (60 ml) unsalted beef stock or broth
- 1 tablespoon (15 ml) oyster sauce
- 1 teaspoon (5 ml) ají amarillo paste
- 1 teaspoon (4 g) cornstarch
- 1 tablespoon (15 ml) cold water
- 1 teaspoon (5 ml) neutral oil, such as canola or sunflower oil
- 1 small garlic clove, finely grated or minced (about 1 teaspoon)
- ¼ teaspoon freshly ground black pepper
Instructions
- In a small bowl, whisk the soy sauce, red wine vinegar, beef stock, oyster sauce, and ají amarillo paste until combined. In a second small bowl, stir the cornstarch into the cold water to make a smooth slurry; set both bowls near the stove.
- Heat the neutral oil in a small saucepan over medium heat. Add the garlic and black pepper and cook for about 20 seconds, stirring constantly, just until fragrant. Do not let the garlic brown, which can make the sauce taste bitter.
- Pour in the soy-vinegar mixture and bring it to a gentle simmer, stirring. Cook for 2 minutes so the flavors mingle. Whisk the cornstarch slurry again, then slowly pour it into the pan while stirring.
- Simmer for 1 to 2 minutes, stirring, until the sauce lightly coats the back of a spoon. It should be pourable rather than thick like gravy. Remove from the heat and taste; add a teaspoon of water if it is too concentrated, or a small splash of vinegar if it needs more tang. Use immediately, or cool and refrigerate promptly.
Tips
- Choose the right vinegar. Red wine vinegar gives a clean, sharp tang. White vinegar works in a pinch but tastes more forceful, so start with 1½ tablespoons (22 ml) and add more to taste. Avoid sweetened rice vinegar unless you reduce or omit any added sweetener in the rest of your dish.
- Adjust the chili carefully. Ají amarillo is a fruity Peruvian yellow chile paste; it is sold in Latin American groceries and some larger supermarkets. If you cannot find it, use ½ teaspoon (2.5 ml) of a mild yellow chili paste or a pinch of cayenne. The substitute will change the flavor, so add it gradually. For a mild sauce, omit it.
- Keep the sauce balanced. Soy sauce and oyster sauce are both salty, so use unsalted stock and taste before adding any extra salt. If the sauce tastes too salty, loosen it with a tablespoon of stock or water rather than adding sugar first.
- Make it ahead, not in the pan with the meat. This sauce can be mixed a day ahead. For classic lomo saltado, cook beef and vegetables quickly over high heat, then add only enough sauce to coat them at the end; excess liquid can steam the ingredients and soften the fries.
Serving Suggestions
This is a sauce for lomo saltado, not a stand-alone gravy: toss it with seared strips of beef, red onion, and tomato during the final minute of stir-frying. Peruvian-style lomo saltado is commonly served with crisp French fries and white rice, often with the fries on the side or briefly tossed into the pan. Add chopped cilantro if you like, and serve promptly so the fries retain some crunch.
The sauce recipe makes about ½ cup (120 ml), enough to season roughly 1 pound (450 g) of beef with vegetables for four servings. If cooking in batches, return everything to the pan before adding the sauce so it heats through evenly. A squeeze of lime at the table is optional; it adds fresh citrus but is not needed for the sauce to taste balanced.
Variations
More heat: Add another ½ teaspoon (2.5 ml) ají amarillo paste, or serve with sliced fresh chile. Chile pastes vary in intensity, so increase in small amounts.
No oyster sauce: Leave it out and add 1 teaspoon (5 ml) more soy sauce plus 1 teaspoon (5 ml) water. The result will be less rounded and slightly less savory. For a vegetarian version, use vegetable stock and a vegetarian mushroom-based stir-fry sauce in place of oyster sauce.
Gluten-free: Use certified gluten-free tamari instead of soy sauce and check that the oyster or mushroom sauce and stock are also gluten-free. Tamari can be saltier, so taste before adding extra.
Without cornstarch: Omit the slurry and simmer the sauce for an extra minute or two. It will be thinner, which is traditional in many quick pan versions and works well when tossed with the other ingredients.
Storage and Reheating
Cool leftover sauce promptly and refrigerate it in a clean, covered container within 2 hours of cooking. Keep it refrigerated for up to 3 to 4 days, or freeze it for up to 2 months for best quality. Thaw frozen sauce in the refrigerator. Do not leave it at room temperature for extended storage.
Reheat only the amount needed in a small saucepan over low heat, stirring until steaming hot; add a teaspoon or two of water or stock if it has thickened. If reheating a complete leftover lomo saltado with cooked beef, bring the leftovers to 165°F (74°C), checking with a food thermometer, in line with USDA FSIS guidance. The fries will soften after storage, so reheat them separately in an oven or air fryer if you want them crisp.
Frequently Asked Questions
What does lomo saltado sauce taste like?
The flavor is savory and salty from soy and oyster sauce, tangy from vinegar, and gently aromatic from garlic and black pepper. Ají amarillo adds a mild, fruity chile note rather than overwhelming heat.
Can I make lomo saltado sauce without oyster sauce?
Yes. Omit it and add a little extra soy sauce and water, as described in the variations. The sauce will still be tasty, though it will have less depth; a vegetarian mushroom stir-fry sauce is a useful alternative.
Can I use this as a marinade?
It is designed as a quick finishing sauce, not a long marinade. Its salt and vinegar can affect the texture of beef if left on too long, and the cornstarch makes it better suited to coating food in the pan. If you want to season beef ahead, reserve the sauce separately and add it during cooking.
Why did my sauce turn lumpy?
Usually the cornstarch was added without first being mixed into cold water, or the slurry was poured in too quickly. Make a smooth slurry, stir it again just before using, and stream it into gently simmering sauce while whisking.
Can I make it less salty or less sour?
For less salt, choose low-sodium soy sauce and unsalted stock, then adjust after simmering. For less acidity, reduce the vinegar slightly and replace the missing volume with stock. Avoid adding lots of sugar; the sauce is meant to be savory and bright.
How much sauce should I use in a stir-fry?
Start with about ⅓ cup (80 ml) for 1 pound (450 g) beef and vegetables, then add more to taste. The full batch yields about ½ cup (120 ml); using all of it gives a more saucy result, especially if serving with rice.
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