Preheat your oven to 375°F and line a baking sheet with parchment paper. In a shallow dish, combine ground cumin, cayenne pepper, salt, and black pepper. Coat both sides of the tilapia fillets with this spice mix, then drizzle with olive oil and dot with unsalted butter for richness.

Place the seasoned fish on the prepared baking sheet, then bake in the preheated oven for 20-25 minutes. When done, the fish should be flaky and easily separable with a fork. If you prefer a crispy, browned finish, switch to broil for an extra 3-5 minutes, keeping a close eye to prevent burning.

While the fish is baking, whip up the zesty garlic lime sauce. In a mixing bowl, whisk together the sour cream, mayonnaise, lime juice, garlic powder, and Sriracha until smooth and well blended.

To ensure your small white corn tortillas are warm and pliable, heat a skillet over medium heat. Toast each tortilla for about 30 seconds on each side, or until they become fragrant and slightly charred.

Once the fish is baked to perfection, it’s time to assemble your fish tacos. On each warm tortilla, layer portions of the flaky fish, followed by crunchy cabbage, luscious avocado slices, diced red onion, and optional tomatoes.

Top each taco with a sprinkle of cotija cheese and a drizzle of the zesty sauce. Present your vibrant fish tacos on a platter with lime wedges for added zest.