Pulse green bell peppers, cabbage, onions and tomatoes until minced.
Drain and add to bowl.
Sprinkle with salt, cover and place in fridge for 8 hours.
In separate bowl, mix mustard seed, celery seed, turmeric, sugar, white vinegar and water.
Pour over vegetables and stir.
Pour mixture in a pot and bring to a boil for 5-10 minutes.
Store in refrigerator.