Green Tomato Relish

5lb (2 quarts) sliced green tomatoes
2 quarts sliced onions
1/4 cup pickling salt
Syrup:
3 cups white sugar
3 cups white vinegar
1/4 cup pickling salt (tied in bag)
1 tsp dry mustard
1/4 tsp pepper

Sprinkle pickling salt over layers of tomatoes and onions. Let stand overnight. In morning, drain and rinse. Boil tomatoes and onions with white sugar, vinegar, and pickling spice; cook on low heat and simmer 1 1/2 hours. Just before removing from heat, add dry mustard and pepper. Pour into hot sterile jars and seal. Really good with cold roast pork or beef!!