Peeling and De-Seeding the Tomatoes
For every 15 oz can of tomato sauce + 15 ounce can of diced tomatoes, use 6 large fresh tomatoes. Boil a large pot of water and have a bowl of ice water standing by. Once the water is boiling, place the tomatoes in for a minute or two until you see the skin starting to peel off. Using a slotted spoon, remove the tomatoes and dump them in the ice water. Let them cool for about a minute, then peel the skins off with your fingers. Cut off the tops of the tomatoes so you can see the seed chambers inside. Over a garbage can, squeeze the tomato so the seeds drip out. You can also use your fingers to scoop out the seeds as best you can.
Crushing and flavoring the tomatoes
Cut each tomato in half and place in a large bowl. Using a potato masher, crush the tomatoes. I also use my fingers (they are all covered in tomato goop at this point anyway) to crush them and then go to the masher. Mash until you have a good ratio of sauce to tomato chunks. Add salt, I'd say about two tsp.
Side note: One really cool thing about homemade tomato sauce is that you get to control the salt content. It will still taste great no matter how much salt you put in!
Keep mashing the tomatoes so that the salt dissolves and the consistency is thick but not too chunky. And there you go! Homemade tomato sauce.
It is a little labor intensive. Set aside about 20 minutes to make the sauce. Or, you can make a whole bunch at once and can it or freeze it. I'm going to experiment with canning soon, so I can make sure to have plenty of sauce to last us through the winter!