Kansas City-Style Barbecued Beef Short Ribs

4 pounds beef short ribs
1 medium onion, peeled and minced
4 cloves garlic, pressed
1/4 cup butter
1/4 cup red wine vinegar
1 cup catsup
1 cup water
1 tablespoon Worcestershire sauce
1 tablespoon brown sugar
1 tablespoon honey
2 tablespoons dry mustard powder
1 teaspoon chili powder

Set ribs out of the refrigerator to warm to room temperature.

Preheat grill.

Meanwhile, make sauce. Saut