To marinate pork: Cut pork across the grain into 1/4-inch slices. In bowl, whisk together hoisin sauce, wine, oil, garlic, ginger and five spice. Add pork and toss lightly to coat. Refrigerate, covered, at least 3 hours or as long as 8 hours. Remove pork from marinade, reserving excess marinade. Place pork slices in hotel pan in one layer; bake in 350°F oven for 20 minutes or until cooked, turning and basting after 10 minutes. Cover and keep warm.
For each serving, to order: Split 1 bun in half horizontally. Spread split halves with 1/2 tablespoon hoisin sauce on each half. Sandwich 3 ounces pork in between, garnishing with red and green onions before closing bun.