Place soy margerine, onions, shallot, garlic, cumin, salt and pepper into a large pot. Cook until onions are beginning to brown. Add black beans (hold one can back if you want a chunkier soup) tomatoes, pumpkin and half veggie broth. At this point, I use a handheld tool to puree all ingredients in pot. (You can use a food processor on the beans and tomatoes before you add them to the pot if you prefer.) Add remaining broth, and the sherry. Simmer uncovered until thick enough to coat a spoon, about 40-45 minutes. Before serving, stir in the balsalmic vinegar. Garnish with toasted punpkin seeds if you like. The soup should be smooth and hearty, with a rich flavor.