Slow-Simmered Senegalese Fish Yassa with Caramelized Onions

By AislePrompt Editorial · Published 2026-06-16 · Updated 2026-06-16

A tangy and savory Senegalese dish featuring marinated fish simmered in a rich onion and mustard sauce with lemon and chili heat. This African-inspired seafood recipe, ready in about 110 minutes, pairs yellow onions, thinly sliced, garlic cloves, minced, fresh lemon juice for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 350 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

• 1 lb firm white fish fillets (such as cod or tilapia)
• 3 medium yellow onions, thinly sliced
• 4 garlic cloves, minced
• 1/4 cup fresh lemon juice
• 2 tbsp Dijon mustard
• 3 tbsp vegetable oil
• 1 tsp dried chili flakes
• 1 tsp salt
• 1/2 tsp black pepper
• 1 cup water
• 2 cups, uncooked white rice

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Instructions

1. Step 1: Place 1 lb of firm white fish fillets into a shallow dish. Pour 1/4 cup fresh lemon juice, 2 tbsp Dijon mustard, 4 minced garlic cloves, 1 tsp salt, 1/2 tsp black pepper, and 1 tsp dried chili flakes over the fish. Marinate for at least 1 hour in the refrigerator to tenderize and infuse flavor.
2. Step 2: Heat 3 tbsp vegetable oil in a large skillet over medium heat. Add 3 thinly sliced medium yellow onions and sauté for 12-15 minutes until deeply caramelized and golden brown, stirring occasionally to prevent burning.
3. Step 3: Remove onions and set aside. In the same skillet, add the marinated fish along with 1 cup water and the caramelized onions. Cover and simmer gently over low heat for 15-20 minutes until the fish is cooked through and the sauce thickens slightly.
4. Step 4: While the fish simmers, cook 2 cups uncooked white rice in 4 cups boiling salted water until tender, about 15 minutes, then drain.
5. Step 5: Serve the fish yassa hot, spooning the tangy onion sauce over the rice for a complete Senegalese-inspired meal.