3 to 4 lbs. bottom round or sirloin tips
1/4 c. white vinegar
3 tbsp. ketchup
3 tbsp. oil

Cut beef into 1 inch cubes. mix vinegar, ketchup and oil in large bowl. Add beef cubes and stir to coat. Marinate meat for 3 to 4 hours in refrigerator.

Place cubes on skewers (about 8 to 10) leaving room between pieces.

Grill over hot coals for 20 to 25 minutes, turning to cook evenly.