In a large bowl, combine the black beans with the next 8 ingredients and set aside.
Cut the pumpkin in half. Set aside one half for another use and peel the other half. Cut it into very thin slices about 1/4-inch thick and 2 inches long.
Preheat oven to 425F. Line a 2-quart casserole dish with parchment paper (or wipe it with a tiny bit of oil, if you desire.) Lay one-third of the pumpkin slices in the bottom of the dish, and sprinkle lightly with salt and pepper. Cover with half of the bean mixture. Repeat layers with another third of the pumpkin and the remainder of the beans. Finish with the final third of the pumpkin slices.
In a blender, combine the reserved *tomato liquid (about 1/2 cup) with the soymilk and remaining ingredients. Blend well and pour over the pumpkin. Cover tightly, and bake for 30 minutes. Remove the cover and bake for 20-30 minutes, until sauce is thick and bubbly and pumpkin is tender.
*If you prefer to use fresh tomatoes, use one cup of chopped tomatoes and substitute 1/2 cup of water for tomato juice in the sauce recipe.