Italian Fish and Vegetable Stew Recipe

Ingredients

• 1 lb. firm white skinless fish fillets (such as mahi-mahi, cod, or halibut), cut into 2" pieces
• Kosher salt, freshly ground pepper
• 1 Tbsp. fresh lemon juice
• 1 Tbsp. red wine vinegar
• 1/2 tsp. Dijon mustard
• 3 Tbsp. extra-virgin olive oil, divided
• 1 cup dry or instant polenta (coarse cornmeal)
• 1 garlic clove, smashed
• 1 medium yellow bell pepper, seeds and ribs removed, cut into 2" pieces
• 1 medium zucchini, cut into 2" pieces
• 1 pint cherry or grape tomatoes, halved
• 1 Tbsp. slivered fresh basil (or 1 tsp. dried), plus whole leaves for serving
• 1 tsp. chopped fresh oregano (or 1/2 tsp. dried), plus whole leaves for serving