Ingredients:4 cups mixed bell peppers, thinly sliced2 large onions, thinly sliced1 cup white vinegar1 cup apple cider vinegar1 cup granulated sugar1 tablespoon mustard seeds1 teaspoon celery seeds1 teaspoon turmeric powder1 teaspoon salt1/2 teaspoon ground black pepper1/2 teaspoon red pepper flakes (optional)Instructions:In a large bowl, combine the sliced bell peppers and onions.In a medium saucepan, combine the white vinegar, apple cider vinegar, sugar, mustard seeds, celery seeds, turmeric powder, salt, black pepper, and red pepper flakes (if using).Bring the mixture to a boil over medium heat, stirring until the sugar dissolves.Pour the hot vinegar mixture over the sliced peppers and onions. Stir well to combine.Let the relish cool to room temperature, then transfer to airtight containers or jars.Refrigerate for at least 24 hours before serving to allow the flavors to meld.Enjoy!