Think of tomatoes (ripe or not) as "fruit" and follow the directions for most jams - 3C prepared fruit (peeled, deseeded, chopped/diced), 7 1/2 C sugar, bit of lemon juice = 1/4C; bring to a boil then add 1 pouch liquid pectin, back to a full boil counting for 1 min. Fill jars and BWB 10.

My most delicious tomato jams use golden heirloom tomatoes (Persimmon, Yellow Pear, Azoychka, Roman Candle) but any unripe green tomato will also be quite delicious, I just prefer ripe fruit.

Nancy