Using a large, heavy pot, melt the butter over low heat. Add the red onion, green onions, tomato, and celery. Cook over low heat for 7 minutes. Increase the heat and bring the water to boiling. Add the potatoes, reduce the heat to simmer, and cool 50 minutes. Stir in the crab meat and the remaining ingredients. Cook, stirring frequently, until the soup returns to simmering boil. Serve immediately.