1 1/2 lbs. Italian plum tomatoes
1/2 lg. red onion
1/2 green bell pepper, seeded
1/2 red bell pepper, seeded
3/4 c. red wine vinegar
6 tbsp. sugar
1/4 c. balsamic vinegar
1 tbsp. minced garlic
Pinch of cayenne pepper
Salt

Prepare barbecue grill (medium-high heat). Grill tomatoes until lightly charred, turning occasionally, about 12 minutes. Grill onion until lightly charred, about 15 minutes per side. Grill peppers, skin side down, until charred, about 8 minutes. Wrap peppers in paper bag and let stand 10 minutes to steam. Peel peppers. Coarsely chop tomatoes, peppers, and onion.

Combine vegetables with all remaining ingredients in heavy large saucepan. Cook over low heat, stirring until sugar dissolves. Increase heat and bring to boil, stirring frequently. Reduce heat and simmer gently until mixture thickens and mounds in spoon, stirring frequently, about 45 minutes. Puree ketchup through fine blade of food mill, discarding skins and seeds. Serve at room temperature.