Preheat oven to 200 degrees. Score the duck skin with a sharp knife. Season both sides of the breast with salt, but only put pepper on the flesh side. Place breast in a cold saute pan and place over low heat. As fat renders out of the skin, drain it off. When skin is crisp and golden, increase flame to medium and turn breast over. Add 2 of the thyme sprigs, the garlic clove and about 2 tablespoons butter. Finish cooking the breasts until medium rare. Remove from the pan and hold in a 200 degree oven. Drain off excess fat from pan. Add shallots and cook until translucent, about one minute. Add port, remaining thyme sprigs, ground coriander seeds and vinegar. Reduce until almost all the liquid is gone. Whisk in cold unsalted butter cubes in small additions. If emulsion becomes too thick , add a touch of chicken stock or water. Strain and keep in a warm, not hot, place. Saute in butter or vegetable oil the turnips until golden or tender. Season with salt and black pepper. Drain on paper towels and keep warm. Repeat the process with the grapes. Drain on paper towels and keep warm. To serve, slice the duck breast thinly. Arrange on warm plates (not too hot, or your emulsion may break). Mix together the emulsion, turnips, and grapes. Spoon over the duck and serve immediately. Garnish with fresh thyme leaves, chervil pluches, or chive points.