Preheat the oven to 375 degrees F. Place the potatoes in a bowl and toss in the oil, cumin, paprika and cayenne pepper. Spoon the potatoes into a large roasting pan. Roast 45 minutes, stirring occasionally, or until just tender. Spoon the potatoes into a salad bowl. Toss in the lemon juice, mustard, green onions and parsley. Serve warm or at room temperature.