Roasted Tomato Sauce

1. Adjust oven rack to middle position and heat oven to 475 degrees. Combine tomato paste, 1 tablespoon oil, thyme, 3⁄4 teaspoon salt, 1⁄4 teaspoon pepper, and pepper flakes in large bowl. Add tomatoes, onion, and garlic and toss until evenly coated. Place 4-inch square of aluminum foil in center of wire rack set in foil-lined rimmed baking sheet. Place garlic cloves and onion rounds on foil and arrange tomatoes, cut side down, around garlic and onion. Roast until vegetables are soft and tomato skins are well charred, 45 to 55 minutes.
2. Remove baking sheet from oven and cool for 5 minutes. Transfer garlic and onion to food processor and pulse until finely chopped, about 5 pulses. Add tomatoes, vinegar, and remaining 1 tablespoon oil to food processor and pulse until tomatoes are broken down but still chunky, about 5 pulses, scraping down bowl as needed. Season mixture with salt, pepper, and sugar to taste and pulse until sauce is slightly chunky, about 5 pulses. Transfer mixture to bowl and stir in basil.

ROASTED TOMATO SAUCE WITH FENNEL
Add 1⁄2 teaspoon fennel seeds to tomato paste mixture. Replace onion with 1 small fennel bulb, sliced 1⁄2 inch thick.

ROASTED TOMATO SAUCE WITH ROSEMARY AND GOAT CHEESE
Substitute 1 teaspoon minced fresh rosemary for thyme. Omit basil. After tossing sauce with pasta, sprinkle with 2 ounces crumbled fresh goat cheese.