Prep the tomatoes - Remove the core from the tomatoes and peel away any blemishes. Chop into a rough dice.
Simmer - Add the tomatoes, salt, sugar, oregano, garlic powder, and tomato paste to a medium saucepan. Cook, stirring occasionally, until the tomato chunks have given up their water. Blend into a sauce with an immersion blender, then continue cooking until the sauce is thick and spreadable, and not at all watery (about 35 minutes).
Store in jars - Pour into clean half-pint jars and stash into the freezer until ready to use.