Slow-Simmered Senegalese Fish Yassa with Lemon and Onions

By AislePrompt Editorial · Published 2026-06-25 · Updated 2026-06-25

A traditional West African dish featuring tender fish marinated in a tangy lemon and onion sauce, slow-cooked to develop deep, vibrant flavors. This African-inspired seafood recipe, ready in about 105 minutes, pairs fresh lemon juice, yellow onions, thinly sliced, garlic cloves, minced for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 320 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.

Ingredients

• 2 pounds whole fish (snapper or sea bass), cleaned and cut into 6 pieces
• 1/2 cup fresh lemon juice
• 3 medium yellow onions, thinly sliced
• 4 garlic cloves, minced
• 2 tbsp Dijon mustard
• 4 tbsp vegetable oil
• 1 tsp dried chili flakes
• 1/2 tsp black pepper
• 1 1/2 tsp salt
• 1 cup water
• 2 tbsp fresh parsley, chopped

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Instructions

1. Step 1: In a large bowl, combine 1/2 cup fresh lemon juice, 3 thinly sliced yellow onions, 4 minced garlic cloves, 2 tbsp Dijon mustard, 1 tsp dried chili flakes, 1/2 tsp black pepper, and 1 1/2 tsp salt. Add the 2 pounds of fish pieces and toss gently to coat. Marinate for at least 1 hour in the refrigerator.
2. Step 2: Heat 4 tbsp vegetable oil in a large skillet over medium heat. Remove the fish from the marinade, reserving the onions and liquid. Sear the fish pieces for 3 minutes on each side until lightly browned but not fully cooked, then transfer to a plate.
3. Step 3: In the same skillet, add the reserved onions and marinade liquid along with 1 cup water. Cook over medium heat, stirring occasionally, until the onions are soft and fragrant, about 10 minutes.
4. Step 4: Gently nestle the seared fish pieces back into the skillet, cover, and reduce heat to low. Simmer for 15-20 minutes until the fish is cooked through and the sauce thickens slightly.
5. Step 5: Sprinkle 2 tbsp chopped fresh parsley over the dish before serving. Serve with steamed rice or couscous to soak up the vibrant sauce.