1. To prepare steak, combine first 5 ingredients in a small bowl. Score a diamond pattern on both sides of steak. Rub chili powder mixture evenly over steak. Cover and chill 1 hour.
2. Prepare grill to medium-high heat.
3. Place steak on a grill rack coated with cooking spray; grill 8 minutes on each side or until desired degree of doneness. Remove from heat; let stand 10 minutes. Cut steak diagonally across grain into thin slices.
4. To prepare salsa, combine avocado and next 7 ingredients (through pepper sauce) in a medium bowl.
5. Warm tortillas according to package directions. Spoon steak mixture evenly over each of 8 tortillas. Top each taco with 1/4 cup salsa and 1/4 cup cabbage.