Chow Chow (Old Fashioned)

Name: Chow Chow (Old Fashioned)
Prep time: 4 h
Cook time: 1 h
Total time: 5 h
Cuisine: Southern
Ingredients: 5 cup(s) coarsely chopped green tomatoes; 5 cup(s) coarsely chopped cabbage; 1 1/2 cup(s) finely chopped yellow onion or sweet onion; 2 cup(s) coarsely chopped bell pepper 1 red for color; 1/3 cup(s) kosher salt or pickling salt; 2 1/2 cup(s) cider vinegar; 1 cup(s) light brown sugar, packed; 1 tablespoon(s) yellow mustard seeds; 2 clove(s) garlic, finely minced; 1 teaspoon(s) celery seed; 1/2 teaspoon(s) red pepper flakes, or to taste, optional