Heat grill to high (450° to 550°). Combine seasonings in a small bowl. Set fish on a rimmed baking sheet. Rub all over with oil, then sprinkle with seasonings. Oil cooking grate, using tongs and a wad of oiled paper towels.
Grill fish, covered, turning once, until just cooked through, 4 to 6 minutes total. Break fish into large chunks. Fill tortillas with slaw and fish. Serve with tartar sauce.
*If tortillas are very thin, buy double the amount and stack 2 per taco.
Note: Nutritional analysis is per taco with 1 tbsp. sauce.