Slow-Simmered Senegalese Fish Yassa with Tangy Onion Marinade

By AislePrompt Editorial · Published 2026-08-06 · Updated 2026-08-06

How this recipe was made — this recipe was drafted by AislePrompt's AI-assisted pipeline from technique templates and USDA-sourced nutrition data, and published by AislePrompt Editorial — see how AislePrompt recipes are drafted and published.

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 recipe, 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

1 pound firm white fish fillets
3 medium, thinly sliced yellow onions
1/4 cup fresh lemon juice
2 tablespoons Dijon mustard
3 minced garlic cloves
3 tablespoons vegetable oil
1/2 teaspoon black pepper
1 teaspoon salt
1 cup water
2 bay leaves

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Instructions

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.
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.
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.
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.