Mustard-Roasted Potatoes

1. 3 medium-large baking potatoes (slightly less than 2 pounds)
2. 3 tablespoons mustard
3. 2 tablespoons olive oil
4. 2 tablespoons freshly grated Parmesan cheese (optional)
5. Freshly ground pepper

Preheat oven to 425 F. Wash and scrub the potatoes. Dry well and cut lengthwise into halves, then into quarters. Cut the quarters lengthwise into halves or thirds (depending on size of potatoes). Combine the mustard, oil and cheese in a large bowl; whisk to blend. Add the potatoes and turn to coat. Spread the potatoes on a lightly greased or sprayed baking sheet. Grind pepper over them. Bake for 35 to 40 minutes, or until browned and tender.