fresh vine-ripened tomatoes
1/2 tsp salt per pint (1 tsp per quart)
I sometimes can the tomatoes whole, but often let them simmer on the stove after peeling them. As they simmer, they will break up slowly and become a sauce that grows thicker the longer it simmers. I like to reduce the liquid in mine by almost half by simmering for several hours. Be sure to simmer very slowly, watch it carefully and stir frequently to prevent scorching.
To prepare tomatoes:
Cut the cores out of the tomatoes. Put a big pot of water on the stove and, when boiling, place tomatoes carefully into it. Keep them covered, and in a few minutes when you see the skins start to split and peel off, take the tomatoes out of the water with a slotted spoon and place in a colander to drain. When cool enough to handle, take the skins off the tomatoes (you can use your hands, the skins come off easily) and place peeled tomatoes in a large cook pot. Simmer on low.
Put lids in a pan, cover with water and simmer for 10 minutes. Wash jars and screw caps, keep in simmering water until ready to fill jars. Heat the tomatoes until the liquid is boiling (if you are making sauce, it needs only to be simmering). Fill the jars up to 1" from the top. Wipe rim of jar with a clean, damp paper towel to be sure there is no food residue. Immediately place a lid, rubber-side down, over top of jar, and seal with screw cap by screwing down as tightly as possible. Process in boiling water bath, 35 minutes for pints, 45 minutes for quarts.
Kerr canning jars can be found at most grocery stores. European canning jars can be ordered online at Weck Jars.