Cook beef on medium heat. Drain well and return to pan. Mix in the chili powder and pepper; cook for about 1 minute. Stir in ¼ cup salsa; heat through.
Warm the tortillas in the oven for a few minutes and spoon on meat mixture. Top with lettuce, cheese, and the remaining ¼ cup of salsa. Roll up and tie each taco with an onion strip.