Because some tomatoes will release more juices than others, the amount of flour you will need may vary from 3 cups to 3 1/2 cups. I started with 3 cups, and then added 1/4 cup more as I brought the dough together with my hands. You can always add more flour, so add the extra 1/2 cup a little at a time when mixing and stop when the dough has come together.