Ingredients
1/3 cup extra-virgin olive oil
2 medium onions, cut into 1/4-inch pieces (2 3/4 cups)
4 cloves garlic, minced (about 2 tablespoons)
6 tablespoons tomato paste
1 batch (about 10 cups) Tomato Puree
3 basil sprigs
Kosher salt, freshly ground pepper, and red-pepper flakes
Preparation
Heat oil in a large pot over medium heat. Add onions and garlic and cook, stirring occasionally, until onions are very soft and translucent, 10 to 15 minutes. Add tomato paste and cook 2 minutes more. Add tomato puree and basil. Bring to a boil, then reduce heat and simmer, stirring occasionally, until flavors meld and sauce has reduced to 8 cups, about 1 hour 15 minutes. Season to taste with salt, black pepper, and red-pepper flakes. Let cool to room temperature, about 1 hour.
Portion into jars, leaving 1/2 inch of headspace. Freeze until ready to use, up to 1 year.
