Slow-Simmered Senegalese Fish Yassa with Tangy Onion Marinade

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

A traditional Senegalese dish featuring tender fish marinated in a vibrant lemon and mustard onion sauce, slowly cooked to infuse flavors. This african-inspired seafood ready in about 100 minutes pairs firm white fish fillets, yellow onions, fresh lemon juice for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 280 calories and feeds 4, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Prep: 70 min Cook: 30 min Serves 4 African cuisine 280 cal/serving
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Ingredients

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Instructions

  1. Step 1: In a large mixing bowl, combine 1/4 cup fresh lemon juice, 2 tablespoons Dijon mustard, 3 minced garlic cloves, 1 teaspoon salt, and 1/2 teaspoon black pepper. Add 3 thinly sliced medium yellow onions and mix well to coat. Add 1 pound firm white fish fillets and marinate for 1 hour in the refrigerator, turning occasionally.
  2. Step 2: Heat 3 tablespoons vegetable oil in a large skillet over medium heat. Remove fish from marinade (reserve marinade) and sear fish fillets for 3 minutes on each side until lightly golden but not fully cooked; transfer fish to a plate.
  3. Step 3: Add the marinated onions and 1 cup water with 2 bay leaves to the skillet. Simmer the onion mixture over medium-low heat for 10 minutes until onions are tender and fragrant.
  4. Step 4: Gently nestle the seared fish fillets into the onion sauce, pour reserved marinade over the fish, cover, and cook for an additional 15 minutes on low heat until fish is opaque and the sauce thickens slightly.

Frequently asked questions

How long does Slow-Simmered Senegalese Fish Yassa with Tangy Onion Marinade take to make?

Total time is about 100 minutes (70 min prep + 30 min cook). Most home cooks find this fits comfortably into a weeknight; double the batch on Sunday for two dinners.

How do I store leftover Slow-Simmered Senegalese Fish Yassa with Tangy Onion Marinade?

Refrigerate in a covered airtight container for up to 3–4 days (FDA FoodKeeper guideline for cooked fish). Store any fresh salsa or citrus-based garnish in a separate container — it keeps for up to 2 days. Freeze cooked fish (without fresh garnishes) for up to 3 months; thaw overnight in the fridge and reheat gently at 275°F until just warmed through to preserve texture.

Can I substitute ingredients in Slow-Simmered Senegalese Fish Yassa with Tangy Onion Marinade?

Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.

How do I scale Slow-Simmered Senegalese Fish Yassa with Tangy Onion Marinade for a different number of people?

The recipe is written for 4 servings. Multiply each ingredient by (your serving target / 4). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.

What goes well with Slow-Simmered Senegalese Fish Yassa with Tangy Onion Marinade?

African seafood like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.

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