Bake the sweet potatoes for about an hour at 400°F. Remove from the oven and reduce the heat to 350°F. When cool enough to handle safely, peel the sweet potatoes and cut into cubes.
While the potatoes are cooling: Mix the allspice, ginger, salt, pepper and chili powder together in a small bowl. Set aside.
Measure the contents of the glaze into a small saucepan and bring to a boil while stirring regularly. Remove from heat.
Place the potatoes, onions and peppers in a large mixing bowl. Sprinkle with half the seasoning. Stir to combine. Add the glaze and the remainder of the seasoning.
Bake for an additional 20 - 30 minutes, or until the vegetables are cooked to your liking. Stir occasionally to distribute the glaze.
Garnish with the cilantro before serving. Serve with rice if you like.