Step 1

Wash tomatoes. Core and cut tomatoes into quarters.

Step 2

Place a single layer of tomato quarters in the bottom of a large saucepan. Mash with a potato masher, and heat over medium-high heat until juicy.

Step 3

Add in the remaining tomatoes in 3-4 batches, mashing after each addition. Once all tomatoes are added, simmer until tomatoes are tender and juicy.

Step 4

Remove from heat. Run the tomatoes through a food mill to remove peels and seeds.

Step 5

Return purée to saucepan. Cook purée, uncovered, over medium-high heat until purée thickens, stirring to prevent sticking. Cook until volume is reduced by one-third for a thin sauce, or one-half for a thick sauce.

Step 6

Prepare boiling water canner. Heat jars in simmering water until ready to use, but do not boil. Wash lids in warm soapy water and set aside with bands.

Step 7

Add ¼ teaspoon citric acid or 1 tablespoon bottled lemon juice to a hot pint jar; ½ teaspoon citric acid or 2 tablespoons bottled lemon juice to a hot quart jar. Ladle hot sauce into hot jar, leaving ½-inch headspace. Remove air bubbles and adjust for headspace. Clean jar rim. Center lid on jar and adjust band to fingertip-tight.

Step 8

Place jar on a canning rack in the boiling-water canner. Repeat until all jars are filled.

Step 9

Cover the canner and bring water to a boil. Process pint jars 35 minutes or quart jars 45 minutes, adjusting for altitude. Start timer once the water is at a full, rolling boil.

Step 10

Turn off heat, remove canner lid, and let jars stand 5 minutes. Remove jars and cool for 12-24 hours on a folded towel. Check lids for seal—they should not flex when center is pressed. Label and store jars.