1 12-ounce unpeeled russet potato, well scrubbed, cut into 1-inch cubes
1 12-ounce yam (red-skinned sweet potato), peeled, cut into 1 1/2-inch cubes
2 large carrots, peeled, halved lengthwise, cut crosswise into 1 1/2-inch pieces
3 medium parsnips, peeled, cut into 1 1/2-inch pieces
1 1/2 tablespoons extra-virgin olive oil
3 tablespoons unsalted butter, room temperature
2 tablespoons finely chopped fresh sage
1 garlic clove, pressed
1 4-pound organic chicken
1 teaspoon coarse kosher salt
8 cups coarsely torn red or green mustard greens
1 shallot, minced
1/2 cup dry white wine
1/4 cup water