Barbecued chuck roast

Ingredients:

3 to 4 pound chuck roast, 2-1/2 to 3 inches thick
3 cloves garlic, minced, crushed
1/4 cup red wine vinegar
1/4 cup olive oil
1/3 cup sherry, dry
1 tablespoon soy sauce
1 teaspoon dry mustard
Freshly ground black pepper
2 tablespoons tomato catsup

Preparation:

Mix all marinade ingredients except the catsup.
Pour over the roast and marinate for at least 24 hours.
When grill is ready, remove the roast from the marinade (reserve the marinade) and put it on the grill, 4 to 5 inches from medium coals. Put the cover on the grill.
Mix the catsup into the marinade and baste 4 or 5 times during grilling.
It will take about 1 hour and 15 minutes for the roast to reach 160 degrees.