Cut sweet potato into bite sized pieces, about ½ to 1-inch in size. You want your sweet potato chunks to be roughly uniform in size so they all cook at about the same rate.
Place the cubed sweet potatoes in a large cast iron skillet or on a baking sheet, and drizzle with oil, sprinkle with cumin, salt, and pepper, and toss to coat. Roast in 400° F oven, turning occasionally, for 25-30 minutes, or until crisp and browned outside and just tender inside.
Notes
The recipe is easily doubled as needed, just be careful not to crowd the pan too much or the potatoes will steam, and won't get as crisp and browned.