1Preheat oven to 400 degrees F. Cut off the top 1/2 inch of each garlic bulb to expose ends of individual cloves. Leaving garlic bulbs whole, remove any loose, papery outer layers. Place bulbs, cut ends up, in a 1- to 1 1/2-quart casserole. Drizzle bulbs with 1 tablespoon of the oil; cover casserole. Arrange sweet pepper halves, cut sides down, on a foil-lined baking sheet; brush with the remaining 2 tablespoons oil.
2Roast garlic and peppers about 40 minutes or until garlic feels soft and peppers are charred. Cool garlic in casserole on a wire rack. Bring foil up around peppers and fold edges together to enclose. Let peppers stand about 15 minutes or until cool enough to handle. Peel off and discard skins. Chop peppers; set aside.
3Remove garlic cloves from paper skins by squeezing the bottoms of the bulbs. Place garlic cloves in a food processor. Cut peeled tomatoes into chunks; add some of the chunks to the garlic in food processor. Cover and process until chopped.
4Transfer chopped garlic and tomatoes to a 7- to 8-quart stainless-steel, enamel, or nonstick heavy pot. Working in batches, repeat chopping the remaining tomatoes in the food processor. Add all of the tomatoes to pot.
5Add brown sugar, salt, vinegar, and black pepper to tomato mixture. Bring to boiling. Boil steadily, uncovered, for 50 minutes, stirring frequently. Stir in chopped peppers. Boil for 10 to 20 minutes more or until mixture reaches desired consistency (you should have about 11 cups), stirring occasionally. Remove from heat; stir in basil and assorted herbs.
6Spoon 1 tablespoon of the lemon juice into each of six hot sterilized pint canning jars. Ladle hot pasta sauce into jars with lemon juice, leaving a 1/2-inch headspace. Wipe jar rims; adjust lids and screw bands.
7Process filled jars in a boiling-water canner for 35 minutes (start timing when water returns to boiling). Remove jars from canner; cool on wire racks.