Roasted Potatoes Poupon

1/2 cup grey poupon country dijon mustard or grey poupon dijon mustard
1/2 cup olive oil
3 pounds red skinned potatoes, cut into 1-1/2 inch cubes
2 medium onions, sliced (about 1-1/2 cups)
chopped parsley, for garnish

In small bowl, combine mustard and oil. In large bowl, combine potatoes, onions and mustard mixture, tossing to coat well. Spread evenly on baking sheet. Bake at 400 for 45 to 50 minutes or until potatoes are tender and crispy. Garnish with chopped parsley.