The Best Fresh Tomato Sauce

In a large stockpot, heat the 10 pounds plum tomatoes, covered, over high heat, stirring occasionally, until tomatoes dump their liquid. Bring to a boil in covered pot, stirring occasionally, and cook until tomatoes are softened, about 10 minutes.

Preheat oven to 275°F (135°C) and grease several rimmed baking sheets and/or baking dishes with oil. Using a food mill or a stand mixer's vegetable strainer attachment, pass cooked plum tomatoes and all their liquid into a large heatproof container. Discard skins and seeds.

Pour plum tomato purée into rimmed baking sheets and/or baking dishes, being careful not to overfill them.

Carefully transfer baking sheets and dishes to oven and bake, checking every 15 minutes and stirring once purée begins to thicken, until a thick, spreadable tomato paste forms, at least 2 hours.

Meanwhile, fill the same large stockpot with remaining 15 pounds mixed tomatoes and cook, covered, over high heat, stirring occasionally, until tomatoes dump their liquid. Bring to a boil in covered pot, stirring occasionally, and cook until tomatoes are softened, about 10 minutes. (Work in batches if your pot can't hold all 15 pounds at once.)

Using food mill or stand mixer's vegetable strainer attachment, pass cooked mixed tomatoes and all their liquid into a large heatproof container. Discard skins and seeds. Measure out 1 quart (900ml) mixed-tomato purée and set aside.

Heat 3 tablespoons (45ml) olive oil in a large, wide saucepan over medium heat until shimmering. Add onion and garlic and cook, stirring occasionally, until softened and sweet, about 8 minutes. Add remaining mixed-tomato purée and simmer, stirring occasionally, until reduced to a sauce-like consistency, 35 to 40 minutes.

Remove from heat; stir in basil and tomato-plant cutting, if using; and let steep for 5 minutes. Discard basil and tomato-plant cutting. Stir in oven-dried tomato paste and reserved tomato purée and season with salt. Use as desired or freeze.