In a large non-reactive mixing bowl, mix together the cabbage, tomato, onion, bell peppers and salt. Mix well, then cover and chill for 8 hours or overnight. Drain liquid.
In a large non reactive pot toast the mustard and celery seeds over medium-high heat about 1 minute or until fragrant, moving pot constantly. Add both vinegars, sugar, mustard, red pepper flakes, allspice, turmeric and ginger. Bring to a boil, then lower the heat and simmer for 10 minutes.
Add the drained cabbage mixture and minced garlic to the pot. Mix well. Increase the heat and bring to a boil for 5 minutes then lower the heat to medium-low and simmer for 20-25 minutes or until slightly thickened, to allow flavors to fully bloom and the juice to reduce. (Cabbage should still have a slight crunch)
Remove from the heat and allow to cool to room temperature in the pot, uncovered. Pack in sterilized jars. May store chilled for up to one month.