Roughly chop onion and zucchini or bell pepper and pulse in a food processor until finely diced.
Set a large soup pot or dutch oven over medium heat and add oil.
Saute the veggies with a pinch of salt and pepper.
Finely mince garlic in the food processor and add to sautéing veggies.
Meanwhile, wash and roughly chop your tomatoes, remove any bad spots and pulse in the food processor, keep some texture, don't totally puree. Transfer each batch to the pot and saute with the other veggies until you've processed all your tomatoes. The amount of tomatoes you use is totally flexible. If you aren't using up garden tomatoes, 2-3 large cans of tomatoes can be used.
Season with salt and pepper and add herbs.
Let sauce simmer, stirring occasionally, bubbling slightly until it reduces to the right consistency, about 1 hour but can vary depending on how many tomatoes you use. You are basically reducing the liquid to make the sauce as thick as you like.
When sauce is done, allow to cool a bit on the stovetop.
IMPORTANT FOR FREEZING IN JARSFill Jars 3/4's Full - this allows the sauce room to expand as is freezes so your jars don't crack.Cool in the Fridge First - Glass doesn't like sudden temperature change, so let your pot of sauce cool slightly on the stovetop before filling your jars, and then let them cool in the refrigerator overnight before moving them to the freezer. Store Sauce in Different Sized Jars or containers - Smaller sized jars can be used for lunch flatbread pizzas or larger jars for pasta dinners, homemade pizza night, whatever your intended use. To Use - Thaw overnight in the fridge.