Prepare the Vegetables : Start by finely chopping 4 cups of green tomatoes, then add 3 cups of green cabbage that has been thinly sliced. Next, prepare 2 cups each of diced red and green bell peppers. Complete the preparation by dicing 1 cup of yellow onion. Using a food processor helps maintain uniform pieces while saving time. Avoid over-processing, as you want the vegetables to retain their crunch.
Salt the Vegetables : Mix the diced vegetables in a wide container made of glass or stainless steel, then add ¼ cup kosher salt over them. Stir thoroughly to ensure the salt is evenly distributed. Cover the bowl and refrigerate overnight (at least 12 hours). This step draws out excess moisture, ensuring a crisp relish.
Rinse and Drain : The next day, rinse the salted vegetables under cold running water to remove the salt. Drain thoroughly in a colander, pressing gently to squeeze out as much liquid as possible. Let it rest until the brine solution is ready.
Make the Brine : Take a large stockpot and mix the following: 2 cups apple cider vinegar, 1½ cups white sugar (granulated), 1 tablespoon mustard seeds (yellow variety), 1 teaspoon celery seeds, and ½ teaspoon ground turmeric powder. Keep stirring the mixture over heat until you notice the sugar has fully dissolved. Once dissolved, reduce the temperature and let the mixture gently simmer for 5 minutes. This cooking process allows all the ingredients to combine properly, creating a harmonious blend of flavors.
Cook the Relish : Mix the filtered vegetables into the pot with the brine solution. Heat the combined mixture while stirring until tiny bubbles start to form on the surface. Turn down the temperature and let the mixture cook gently for 10-15 minutes, occasionally mixing to combine all ingredients. Test the vegetables with a fork - they should be tender enough to pierce but maintain a slight crunch.
Can the Chow Chow : To sanitize your jars, submerge them in boiling water and let them stay there for 10 minutes. Using a canning funnel, ladle the hot chow chow into jars, leaving ½ inch of headspace. Wipe the jar rims clean, securely fasten the lids, and place them in boiling water for 10 minutes to ensure a proper seal.
Cool and Store : Place the jars on a counter covered with a towel and allow them to cool. Test whether they're adequately sealed by pushing down on the center of each lid - a sealed jar won't make a popping sound when pressed. When stored in a cool, dark location, these jars will remain fresh for a maximum of 12 months. Once opened, you should refrigerate them and use their contents within 90 days.