Stir together cabbage, onion, green tomatoes, chopped green and red bell peppers, and pickling salt. Cover and chill 2 to 8 hours. Transfer mixture to a Dutch oven. Stir in sugar, vinegar, 1/4 cup water, mustard seeds, celery seeds, turmeric, and, if desired, dried crushed red pepper. Bring to a boil over medium-high heat; reduce heat to medium, and simmer 3 minutes. Cool to room temperature (about 30 minutes). Stir in jalapeño pepper, if desired. Cover and chill 1 to 8 hours before serving.