Rinse tofu and drain in a colander for 5 minutes, then pat dry with paper towels.
Cut tofu into 1-inch cubes and lightly blot with more paper towels.
In a bowl, mix soy sauce, lime juice, chili powder, cumin, garlic powder and cayenne.
Add tofu cubes and mix gently to coat completely. Let stand 5-10 minutes, stirring occasionally.
Meanwhile, mix lettuce with seasoned rice vinegar in another bowl.
Thread marinated tofu cubes equally onto four 8-inch wooden skewers.
Heat a 12-inch nonstick frying pan over medium-high heat.
Cook skewers in hot pan, turning as needed to brown tofu on all sides, 5-6 minutes total.
Stack tortillas and wrap in plastic wrap. Microwave at full power until hot and steamy, 30-45 seconds.
Serve tofu, lettuce mixture, warm tortillas, salsa, and sour cream taco-style.