1. Heat a grill to high (450° to 550°). Mix annatto, oregano, paprika, garlic, and 1/4 tsp. each salt and pepper. Rub 1 1/2 tbsp. oil and 2 tbsp. lime juice over steak and sprinkle both sides with spice mixture.
2. Grill steak, turning once halfway through, 4 minutes total for medium. Let rest 10 minutes. Warm tortillas on the grill, about 45 seconds each, and wrap in foil to keep warm.
3. Combine jicama, apple, cilantro, and remaining 1/4 tsp. each salt and pepper, 1 1/2 tbsp. oil, and 1/4 cup lime juice in a bowl. Slice steak crosswise. Serve slaw and steak with tortillas.
*Find at well-stocked grocery stores; annatto is also at Latino markets.