Trim sprouts, cutting large ones in half. Steam sprouts until just crisp-tender.
Combine seasoning and ground mustard in a small bowl and set aside. Heat the oil in a large sauté pan. Add the Brussels sprouts and stir fry until their edges just begin to turn golden brown, about 1 to 2 minutes. Sprinkle the seasonings over the sprouts. Serve immediately.
Variation: Substitute broccoli for Brussels sprouts.