1 In a food processor, mince the garlic. Add the onion and coarsely chop; set aside.
2 Form the beef into 4 even patties about 3 1/2 inches in diameter and 3/4 inch thick.
3 In a large skillet, warm the oil over medium-high heat until hot but not smoking. Add the burgers and cook for 5 minutes.
4 Turn the burgers over and cook until browned on the second side but still slightly pink in the center, about 4 minutes. Remove the burgers to a plate and cover loosely to keep warm.
5 Add the garlic-onion mixture to the skillet and cook, stirring, over medium heat until the onion begins to brown, about 5 minutes.
6 Add the tomatoes, ketchup, orange juice concentrate, chili powder and pepper. Bring the mixture to a boil over medium-high heat and boil for 1 minute.
7 Return the burgers (and any juices that have accumulated on the plate) to the skillet, baste with some of the sauce, and cook for 1 minute, or until the burgers are heated through.