Start with a red onion, sliced into thin half moons, and a large zucchini (or several small ones) cut into about 1/3 inch thick disks. Saute them in a small amount of extra virgin olive oil just until the onions and zucchini are starting to get soft.
Add a couple of large tomatoes that you have cut into large chunks.
And let them begin to cook down just until they start to soften.
You'll notice them breaking down like this. Put the lid on and let everything simmer for a minute or two to finish cooking...