In a bowl, whisk together olive oil, lime juice, minced garlic, and taco seasoning. Add firm white fish fillets, cover, and marinate in the refrigerator for 20 to 30 minutes.

In another bowl, mix Greek yogurt, lime zest, lime juice, salt, pepper, and cumin to create the dressing. Add shredded cabbage and grated carrot, toss until well combined.

Preheat grill to medium-high and lightly coat grates with olive oil before grilling.

Warm corn tortillas on the grill for about 30 seconds on each side. Keep warm by stacking and covering.

Grill marinated fish for 3 to 5 minutes on each side until opaque. Avoid overcooking.

Flake grilled fish into chunks and place on warm tortillas. Top with cabbage slaw and cilantro. Serve immediately.