Prepare a boiling water canner and 4 pint jars.

Place half the tomato puree in a large stainless steel saucepan. Bring to a boil over high heat, stirring occasionally.

Keeping the puree at a boil, add the remaining tomato puree, 1 cup at a time, until it is all added. Stir in the crushed tomatoes.

Stir in the lemon juice, oregano, black pepper, salt, and garlic powder.

Boil hard, stirring frequently, until the sauce is the consistency of a thin commercial sauce, about 20 minutes. Remove from heat.

Ladle the hot sauce into hot jars, leaving 1/2 inch headspace. Remove air bubbles and adjust headspace. Wipe the rim. Place the lid on the jar and place a screw band on the jar to fingertip tight.

Place the jars in the canner and bring to a boil. Cover the pot and process for 35 minutes.

Remove canner lid and allow to cool 5 minutes. Remove from the boiling water and cool for 24 hours.

Check seals and store for 1 year.