Laura, this is a tasty tomato jam, using Certo. An oldie but good
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Tomato Jam

3 cups prepared tomatoes (about 2 1/4 pounds ripe tomatoes)
1 1/2 teaspoons grated lemon rind
1/4 cup lemon juice (two lemons)
6 1/2 cups sugar
1 bottle Certo (it comes in foil packets now)

First prepare tomatoes. Scald, peel and chop about 2 1/4 pounds fully ripe tomaotes. Bring to a boil and simmer for 10 minutes. Measure 3 cups into a large sauce pan. Add 1 1/2 teaspoons of grated lemon rind and 1/4 cup lemon juice to the tomatoes. To the measured fruit in the pan add the EXACT amount of sugar. Mix well. Place over heat and bring to a full rolling boil and boil hard for one minute stirring constantly. remove from heat;at once stir in Certo. Skim off foam with metal spoon. Then stir and skim for five minutes to cool slightly to prevent floating fruit. Ladle into sterile glasses. I pour into jars and seal and process in a boiling water bath for five minutes. Easier!!!! It is a favorite recipe of mine.