I got this recipe from Steven Raichlen's "The Barbecue Bible". My sister was visiting and we decided to make this for my birthday dinner. This meat is so flavorful. Time doesn't include marinading time.
If using tenderloin tips, butterfly them to obtain broad flat pieces of meat; each should be about 4 inches long and wide and 1/4 in chc thick. If using sirloin, cut is across the grain into 1/4 inch slices. Whichever cut you use, pound the slices between two sheets of plastic wrap with the side of a cleaver or with a rolling pin to flatten them to a thickness of 1/8 inch. Place the meat in a large nonreactive baking dish and set aside while you prepare the marinade. (I just place them in a sealable plastic bag).
Combine all ingredients for the marinade in a small bowl and whisk until the sugar is dissolved. Pour the mixture over the meat in the baking dish and toss to thoroughly coat. Cover and let marinate, in the refrigerator,, for 1 to 2 hours.
Preheat the grill to high.
When ready to cook, oil the grate. Arrange the pieces of meat on the grate and grill, turning with tongs, until meat is nicely browned on both sides, 1 to 2 minutes per side.