There are a few options! My top choice would be to bake the sweet potatoes covered with foil until tender. You can also boil them, but they tend to lose flavor and come out more watery. You can also steam them in the microwave. Place the pieces in a large, microwave-safe bowl (Pyrex is great for this), add some water, and cover tightly with plastic wrap.   Microwave a minute or two at a time until the sweet potato chunks are fork-tender. Then, drain off the liquid and use as directed.