Steam or boil the sweet potato cubes until just tender.
Meanwhile, sauté the garlic, ginger, and spices in oil for one minute. Add the onions and cook until they begin to soften. Add the tomatoes, eggplant and a small amount of vegetable stock or water and simmer for 10 minutes. Add the zucchini and peppers and continue to simmer until all of the vegetables are tender, about 20 minutes.
Drain the sweet potatoes and add them to the stew along with the tomato juice and peanut butter. Stir well. Simmer on very low heat for 5 to 10 minutes, stirring occasionally to prevent sticking.
Serve on rice, couscous or millet. At Moosewood we garnish this stew with hard-boiled egg halves, and pineapple and banana slices.
Variations popular at Moosewood: Substitute 3 cups of chopped green cabbage, and 1 1/2 to 2 cups chopped okra for the eggplant, and add 1 cup of apple or apricot juice and some chopped fresh cilantro leaf.