I got this idea from a recipe for Tomato Jam on paninis from a Portland newspaper - and sort of ran with it. You may not have Green Zebras on hand - but the fresh, ripe mellow flavor of green heirloom tomatoes is really good in this recipe.
2# of peeled, seeded & coarsely chopped tomatoes (drained - reserve the juice for bloody marys, for the love of mike!)
1 c. sugar
2 tsp fresh chopped thyme
1 tsp freshly ground white pepper
4 Tb sherry vinegar
Simmer til slightly thick - you still want to have some nice chunks of tomato - add a bit more sugar if it's not thickening up enough. It shouldn't be jammy sticky and thick - this is for savory sandwiches. Turns out this works really great on fried green tomato poboys.