Fill a stock pot or Dutch oven with about 10 cups of cold water.
Make an ice bath by filling a large bowl with ice and add cold water.
Rinse tomatoes under cold water. With a sharp paring knife, cut a shallow cross over the stem end of the tomatoe.
Once the water is boiling, place one or two tomatoes at a time into the boiling water and let then blance for about 1 to 1 ½ minutes after the water returns to a boil.
Remove the tomato and place it immediately into the ice bath; Once you have blanched all of the tomaotoes, let them sit for no more than 5 minutes in the ice bath
Remove the tomatoes and cut the stem end core out of the tomato with a paring knife.
The skin should be shrinking a little off the tomato. Use the paring knife to grab an edge of the skin and pull it off until it is completely skinned. You may be able to do this with just your hands if the skin is loose enough.
If you want to de-seed the tomato, cut it in half (horizontally) to expose the seed cavaties and scoop out the seeds with a small spoon or your fingers. You can also squeeze the seeds out in lieu of scooping.
Chop the tomatoes into your desired size.