Salmon Karashi Su Miso: Easy Japanese Recipe

Salmon karashi su miso is a Japanese dish where salmon is simmered in a savory-sweet miso sauce brightened with karashi (hot Japanese mustard) and rice vinegar. The combination of rich salmon, salty-sweet miso, and a sharp, sinus-clearing kick from the mustard makes it a quick, flavorful weeknight dinner. It’s a lesser-known but beloved home-style dish that comes together in about 20 minutes, perfect for serving over steamed rice.

Ingredients

4 salmon fillets (about 6 oz / 170 g each), skin on or off
1/2 cup (120 ml) water
3 tbsp (45 ml) sake or dry white wine
2 tbsp (30 ml) mirin
2 tbsp (30 g) brown sugar, packed
3 tbsp (45 g) white or yellow miso paste
1 tbsp (15 ml) rice vinegar
2 tsp (10 g) karashi (Japanese hot mustard) paste, or 1 tsp (5 g) powdered karashi mixed with 1 tsp (5 ml) water
1 tbsp (15 ml) vegetable oil
2 green onions, thinly sliced (for garnish)
Toasted sesame seeds (optional, for garnish)

Instructions

Pat the salmon fillets dry with paper towels. If the fillets have pin bones, remove them with tweezers. Season lightly with salt and pepper.
In a small bowl, whisk together the water, sake, mirin, brown sugar, miso paste, rice vinegar, and karashi paste until the miso and sugar are fully dissolved. Set the sauce aside.
Heat the vegetable oil in a large skillet over medium-high heat. Place the salmon fillets skin-side down (if using skin) and cook for 3–4 minutes, until the skin is crisp and golden. Flip and cook for another 2 minutes. The fish will not be cooked through at this point.
Pour the sauce into the skillet, around the salmon. Bring to a gentle simmer, then reduce the heat to medium-low. Spoon the sauce over the tops of the fillets as they cook.
Cover the skillet and let the salmon simmer for 5–7 minutes, or until the fish flakes easily with a fork and reaches a safe minimum internal temperature of 145°F (63°C) as measured with a food thermometer (USDA FSIS safe minimum for fish).
Remove the salmon to a plate. Turn the heat up to medium-high and let the sauce bubble, stirring frequently, for 2–3 minutes, until it thickens to a glaze-like consistency.
Spoon the glaze over the salmon, garnish with green onions and sesame seeds if using, and serve hot.

Tips

Karashi substitutes: If you don’t have karashi, you can use 1 teaspoon of Dijon mustard mixed with a pinch of cayenne or a few drops of hot sauce. This will change the flavor slightly—Dijon is less pungent and has herbs—but it will still be delicious.
Don’t overcook the salmon: The fish will continue to cook slightly from the residual heat after you remove it from the pan. Cook until it just reaches 145°F (63°C) and no more; it will be juicy and tender. Overcooked salmon becomes dry and chalky.
Balance the salt: Miso paste varies in saltiness. If you use a very salty miso (like some red or aged varieties), start with 2 tablespoons and taste the sauce before adding the salmon. You can always add more, but you can’t take it out.
Skin on or off: If you prefer skinless salmon, sear the fillets on both sides for 2 minutes each instead of the 3–4 + 2 minutes. The skin adds flavor and helps keep the fish moist, but it’s not essential.

Serving Suggestions

Serve the salmon karashi su miso over steamed Japanese short-grain rice to soak up the delicious sauce. A side of blanched greens like spinach or broccoli tossed with a little sesame oil and salt makes a simple, balanced meal. For a heartier dinner, add a bowl of miso soup and a small cucumber salad with rice vinegar.

Variations

Mackerel or sardines: This sauce is also excellent with oily fish like mackerel (saba) or sardines. Adjust the cooking time based on the thickness of the fish; they are done when they reach 145°F (63°C).
Add ginger: Grate 1 teaspoon of fresh ginger into the sauce for an extra layer of warmth and aroma. This is a common addition in some regional versions.
Make it less sweet: Reduce the brown sugar to 1 tablespoon (15 g) if you prefer a more savory, less dessert-like glaze. You can also add a splash of soy sauce (about 1 teaspoon) for extra umami.
Chicken version: Use boneless, skinless chicken thighs instead of salmon. Sear the chicken for 4–5 minutes per side, then simmer in the sauce for 10–12 minutes until the chicken reaches a safe minimum internal temperature of 165°F (74°C) (USDA FSIS safe minimum for poultry).

Storage and Reheating

Leftover salmon karashi su miso can be stored in an airtight container in the refrigerator for up to 3 days. The sauce will thicken as it cools; that’s fine. To reheat, place the salmon and sauce in a skillet over medium-low heat with a splash of water or sake, and heat gently until warmed through (about 5 minutes). Alternatively, microwave individual portions in 30-second bursts at 50% power to avoid overcooking the fish. The fish will be best the first day, but it’s still tasty the next day flaked over rice or in a rice bowl.

Frequently Asked Questions

What is karashi? Karashi is a Japanese hot mustard made from ground brown mustard seeds. It’s much spicier than Western yellow mustard, with a sharp, sinus-clearing heat that dissipates quickly. It’s sold as a paste in tubes or as a powder that you mix with water. If you can’t find it, a good substitute is a mix of Dijon mustard and a pinch of cayenne.

Can I use a different type of miso? Yes. White (shiro) miso is the mildest and sweetest, making it ideal for this dish. Yellow (awase) miso is a blend of red and white and works well too, giving a slightly stronger flavor. Red (aka) miso is saltier and more intense; if you use it, reduce the amount to 2 tablespoons and taste before adding more.

Is it okay to eat the skin? Absolutely. The skin becomes crisp during the initial sear and is delicious. If you prefer not to eat it, it’s easy to remove after cooking—it will slide off the flesh with a fork.

Can I make the sauce ahead of time? Yes, you can whisk together the sauce ingredients (water, sake, mirin, sugar, miso, vinegar, karashi) up to 2 days in advance and store it in the refrigerator. Give it a good stir before using. The karashi may lose a little of its punch, so you might want to add a bit more fresh karashi right before cooking.

What if I don’t have sake? You can substitute dry white wine or even a splash of chicken or vegetable broth mixed with a teaspoon of lemon juice. Sake adds a subtle sweetness and depth, but the dish will still be delicious without it.

Can I grill or broil the salmon instead of pan-searing? Yes. To make a grilled version, marinate the salmon in the sauce for 30 minutes, then grill or broil until cooked through, brushing with extra sauce as it cooks. The glaze may char slightly, which adds a nice smoky flavor. Just be careful not to burn it.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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