In medium bowl, combine ground beef, jalapeno pepper and chili powder, mixing lightly but thoroughly.
Shape beef mixture into four 1/2-inch thick patties.
Place patties on grid over medium ash-covered coals. Grill uncovered 14-16 minutes or until centers are no longer pink, turning once. Check with a meat thermometer for an internal temperature of 160°F.
Approximately 1 minute before burgers are done, sprinkle each with 1 Tbsp. cheese.
Place one slice tomato on bottom half of each bun and top with burger. Close sandwiches and serve.
Wear rubber gloves while working with fresh jalapenos to avoid burning your skin.
