Place the roughly chopped bell peppers, cucumbers, and onions into a food processor. Process until minced.
Drain, and transfer to a large bowl. Sprinkle with salt, cover, and rest overnight in the fridge.
In the morning, drain the veggie mixture once again.
In a small bowl, mix the mustard seed, celery salt, turmeric, sugar, white wine vinegar, and water to make the relish dressing.
Transfer the veggie mixture into a large pot on the stove.
Add the relish dressing to the pot. Heat over a high flame to boiling, then lower the heat, and allow to boil for 10 minutes.
Remove from the heat, and allow the relish to cool before serving.
