In a bowl, combine together the bell peppers, cabbage, onions, green tomatoes, jalapeño and kosher salt. Cover with plastic wrap and refrigerate overnight. In the morning drain the liquid from the mixture.
In a large dutch oven or pot, toast the mustard seeds and celery seeds until fragrant and beginning to "pop", about 2-3 minutes.
Add in the sugar, apple cider vinegar and 1 cup of water to the toasted seeds and stir until sugar is dissolved. Add in the drained vegetable mixture along with the crushed red pepper, mustard powder, turmeric and ginger, and bring to a boil. Reduce the heat to a simmer and stir occasionally. simmer until the mixture is thick, about 1 hour.
Remove from heat and let cool. The Chow Chow will stay for about a week in the fridge in an air-tight container.
Learn more about Chow Chow here.