Preheat oven to 375. Line a baking sheet with parchment paper.
Slice peppers in quarters. Cut ends off tomatoes and slice in half. Cut onions into quarters.
Toss all vegetables in a large bowl with olive oil, salt and pepper.
Spread out onto parchment paper and roast for 30 minutes, or until beginning to brown.
Allow to cool slightly, and then pulse briefly in food processor with 1-2 tablespoons tomato paste, a drizzle of olive oil, fresh lemon juice and schug.
This sauce should have some chunkiness to it, so pulse briefly and use a spatula to sweep the sides of the bowl if necessary.