Place the fish fillets in a baking dish. Drizzle with olive oil and season with salt and freshly ground black pepper. Bake for 12 to 15 minutes or until the fish flakes easily with a fork.
While the fish cooks, heat 2 tablespoons of olive oil in a frying pan over medium-high heat. Add diced onion and cook until translucent, about 3 minutes. Add minced garlic and cook for 20 seconds or until fragrant.
Whisk in white wine, Dijon mustard, lime zest, and lime juice. Cook until the liquid reduces by half, about 1 to 2 minutes. Add chili powder and whisk in heavy cream. Cook and whisk until the sauce thickens, about 1 to 2 minutes.
Heat a frying pan over medium-high heat. Warm each tortilla for a few seconds on each side.
Break the cooked fish into flakes and place in warm tortillas. Top with cabbage slaw or salad greens and drizzle with the creamy lime mustard sauce before serving.
Notes
For a gluten-free option, use corn tortillas. Add your favorite taco toppings like diced mango, guacamole, or fresh cilantro for extra flavor.