Preheat oven to 400 degrees. Scrub 2 sweet potatoes. Quarter lengthwise; slice diagonally 1 1/2 inches thick. On a rimmed baking sheet, toss slices with 2 tablespoons olive oil, 1 teaspoon dry mustard, 1/2 teaspoon ground ginger, and 1/4 teaspoon cayenne; season with coarse salt. Roast, tossing occasionally, until crisp-tender, 20 to 25 minutes.
Core and quarter 2 Bartlett pears; halve crosswise. Add to the potatoes; toss all with another tablespoon oil. Continue roasting until potatoes are fork-tender, about 10 minutes more.