Fire and Ice Salad

2 large purple onions, cut into 1/4-inch slices
6 large, firm tomatoes, peeled and quartered
1 bell pepper, seeded and cut into strips
3/4 C cider vinegar
1/4 C water
1 1/2 tsp celery seeds
1 1/2 T mustard seed
1/2 tsp salt
2 T granulated sugar
1/2 tsp cracked black pepper

Place onions, tomatoes, and bell pepper in a bowl.  In a saucepan, bring all other ingredients to a boil. Boil for one minute only.  Pour over vegetables and chill.