Sauté garlic slices in 1 or 2 tsp of butter until lightly browned. Set aside, covering to keep warm. Do the same with the shiitake mushrooms. Parboil green beans in lightly salted water. Drain. Lightly sauté in one to two teaspoons of butter. Set aside as well, keeping warm. If desired, you may season each vegetable with salt and pepper. You may also, as an alternative, steam the mushrooms and green beans instead of sautéing them.
Sauté duck breasts in one tablespoon of butter over medium heat. Cook until desired doneness (in this recipe, duck should still be pink inside). Set aside, keeping warm.
To make sauce: Add two tablespoons of butter to the remaining duck drippings and turn heat back to medium. Add orange zest, orange juice, soy sauce, and Grand Marnier. Cook for a few minutes until sauce is reduced, stirring continually. To thicken sauce just before serving, add a tablespoon or two of cold butter and stir until thoroughly combined.
SERVING SUGGESTION: Place garlic, shiitake mushrooms, and green beans along edges of plate, in a half circle. Place duck in the center. Lightly spoon sauce over duck. Top duck with a small mound of perilla leaves. Serve immediately.
VARIATION: Duck can be replaced with beef, such as a filet mignon. This dish is also good served with potatoes, such as potatoes Anna, a traditional French preparation.
