You need tomatoes. About 8 or more. Or enough to fill the bottom of a pot and then some or more. You can cut the large one up and de-seed or leave the seeds in. It is up to you.
I have tried with seeds and with out. Put the top of the pot of tomatoes and turn the heat on to medium. Bring to a boil and then simmer for 3-5 minutes or until tomatoes are soft.
Now take out you mixer and let this sauce simmer. Reduce it to about half and then turn off the heat and let cool.