Preheat a grill for medium heat. When hot, lightly oil the grate.
In a medium bowl, lightly mix together the ground beef, barbeque sauce and garlic powder. Separate into 4 portions and flatten into patties.
Grill the burgers for about 8 minutes per side, or until well done. Place a slice of cheese on top of each burger and allow it to melt for a minute. Press chopped cilantro into the melted cheese on each burger. Serve burgers on toasted sourdough bread topped with lettuce and tomato. Feel free to use other condiments to your liking.