In a small bowl, mix together garlic, salt, soy sauce, ketchup, vegetable oil, black pepper and oregano.
Score both sides of the meat, diamond cut, about 1/8 inch deep. Rub garlic mixture into both sides of the meat. Wrap tightly in aluminum foil, and refrigerate for 5 to 6 hours, or overnight. Flip meat every few hours.
Preheat an outdoor grill for high heat, and lightly oil grate.
Place meat on the prepared grill. Cook for 3 to 7 minutes per side, or to desired doneness.