Spiced Grilled Chicken

2 tablespoon cooking oil
1/4 cup onion -- chopped fine
1 each clove garlic -- minced
3/4 cup ketchup
1/3 cup vinegar
1 tablespoon Worcestershire sauce
2 teaspoons brown sugar
1/2 teaspoon celery seed
1 teaspoon dry mustard
1/2 teaspoon salt
1/4 teaspoon black pepper
1 teaspoon Tabasco sauce
1 each 2 1/2-3 pound chicken quartered

Heat cooking oil in saucepan and cook onion and garlic until tender, but do not brown. Add ketchup, stir, and add remaining ingredients (EXCEPT CHICKEN). Bring to a boil. Reduce heat, simmer, uncovered, for 10 minutes, stirring occasionally. Set sauce aside. Season chicken pieces with additional salt, if desired. Place chicken pieces bone side down over medium to hot coals. Grill 25 minutes (until bone side is well browned). Turn pieces over and grill 25 minutes more (until chicken is tender). Brush chicken frequently with sauce during last 10 minutes of grilling, using all the sauce.