In a bowl, whisk together olive oil, lime juice and zest, chili powder, paprika, cumin, salt, and pepper. Add fish fillets and coat evenly. Let marinate for 10–15 minutes while preparing the slaw.
In a large bowl, toss cabbage, mango, red bell pepper, carrot, and cilantro. Drizzle with lime juice and olive oil, season with salt, and mix well. Set aside.
Preheat a grill or skillet over medium-high heat. Lightly oil the surface. Grill fish for 3–4 minutes per side until cooked through and slightly charred. Remove and flake into bite-sized pieces.
In a small bowl, mix yogurt (and mayo if using) with lime juice. Adjust with salt to taste.
Warm tortillas in a dry pan or over the grill for 20–30 seconds per side. Layer each with a spoonful of mango slaw, pieces of grilled fish, and a drizzle of lime yogurt sauce. Garnish with cilantro and an extra squeeze of lime.
