2 tablespoons vegetable oil, like soy, corn or peanut
1/2 medium Spanish onion, chopped
6 cloves garlic, minced
Pinch of crushed red pepper
1 tablespoon tomato paste
1 (28-ounce) can whole, peeled tomatoes (with puree), pureed in a blender
1 cup plus 2 tablespoons red wine vinegar
1 cup firmly packed light brown sugar
1 1/2 teaspoon kosher salt
Freshly ground black pepper
Heat the oil in a medium saucepan over medium-high heat. Add the onion and cook, stirring, until lightly browned, about 4 minutes. Add the garlic and crushed pepper and cook, stirring frequently, until fragrant, about 45 seconds. Add the tomato paste and cook, stirring, until lightly browned, about 1 minute more.
Add the tomatoes, vinegar, sugar, and salt and bring to a boil. Lower the heat, and simmer, uncovered, stirring occasionally, until deep red in color and reduced to about 4 cups, about 25 minutes. Season with pepper to taste. Use now, or store, covered in the refrigerator for up to 3 days or freeze for up to 1 month.