Wash well and cut out the core.Cut into quarters and set aside in a large bowl or pot. Process tomatoes thru a Tomato Sieve or the way I do it is thru my Kitchen Aid tomato strainer.Quickly and easily prepare fresh apple or tomato sauce, baby food, freezer jams, and chutneys when you attach the fruit and vegetable strainer parts to your food grinder attachment.
I use a 21 quart Presto pressure cooker that will fit 7 quarts at a time. The pressure should be @ 5lbs. for 10 minutes.
Let the steam escape on it's own,usually about 15 minutes.Remove the steam lid and set the jars on a cooling rack. Do not put in a cool draft area or run coll water on the jar, they will break.