Stewed tomatoes are very simple to prepare. I just blanch the tomatoes and slip the skin off then chop them into large chunks.
While I am doing that I have the chopped peppers, onions and zucchini sauteing in olive oil- I've already run them through the food processor.
I add in some garlic.
Did I mention I was lucky enough to get to buy some gorgeous local garlic...and not just regular garlic - homelearner garlic! ;-) My family went for a long time this year without any garlic because we ran out of last year's garlic too early and I do not wish to buy the garlic from China that they are selling in our grocery stores. Happily we had a supply of roasted garlic powder made by a generous friend out of last year's garlic and so we were still able to satisfy our taste for local garlic with that (And yes, roasted garlic powder is as delicious as it sounds - we call it "gold" around here and spoon it out very carefully).
Once those veg are all satueed then I add the chopped tomatoes and cook it for a bit then add some herbs - basil, oregano or parsley usually. Add a bit of salt and then let it cool.Then I ladel it into containers (yes, still using plastic containers because I've yet to find something that works better for the quantities that I put by - these I can stack at least 4 high in the freezer).
And that's it. The other thing I love about these over my canned tomatoes is that they already have all the things in that I would normally add to soups, sauces and casseroles (the zuke, onions, peppers, garlic and herbs) so it makes meal preparation throughout the year that much easier.