1 lg. onion
4 tbsp. oil
3/4 c. red wine vinegar
1 tsp. thyme
1/2 tsp. salt
Chuck roast or other meat for marinating

Brown onion in oil, add red wine vinegar, thyme and salt. Heat to boiling. Allow to cool slightly. Pour over meat. Puncture meat on both sides with fork. Let sit at least 6-8 hours. Can be done 2-3 days ahead. Turn and poke meat several times while marinating. Cook over charcoal. Can be basted with BBQ sauce although I usually don't.