Green and Red Tomato Relish

4 pounds green tomatoes, cored and chopped, about 16
4 pounds ripe red tomatoes, cored and chopped, about 16
2 green bell peppers, halved, seeded, and chopped
2 red bell peppers, halved, seeded, and chopped
2 yellow bell peppers, halved, seeded, and chopped
1 cucumber, chopped
3 cups chopped onion
1 cup salt
6 cups cider vinegar
6 cups light brown sugar
1 teaspoon ground cardamom
1 tablespoon mustard seed
1 tablespoon freshly ground pepper

Combine the tomatoes, peppers, cucumber, and onion in a large bowl. Sprinkle with salt. Line a colander with cheesecloth. Place the tomato mixture in the colander and let it drain for 12 to 24 hours in a cool place.

Combine the vegetables with the vinegar, brown sugar, cardamom, mustard seeds, and pepper in a heavy, nonaluminum pot. Bring to a boil, then reduce heat and simmer, stirring occasionally, until thick, about 30 minutes.

Spoon into hot, sterilized pint jars, leaving 1/2-inch headspace. Adjust the lids and process in a boiling-water canner for 5 minutes.

Makes 6 to 8 pints