Heat oil in a medium sauce pot over medium-high heat. Add scallions, ginger, and garlic and saute 30 seconds or until aromatic. Add Chinese rice wine, chicken broth, brown sugar, lemon zest and juice, soy sauce, five-spice powder, and black pepper. Bring to a simmer. Remove from heat and let cool.

Meanwhile, cut pork loin into ½ inch thick slices. Pour half of the cooled sauce over the pork and marinate for 1 hour or overnight. Reserve the remaining marinade for the sauce.

Soak bamboo skewers in water for 30 minutes. Preheat grill to medium heat.

Remove pork from the marinade and skewer the meat. Cook on the grill until grilled marks appear and the pork is no longer pink. Remove from the grill.

Meanwhile, prepare the sauce. Heat the reserved marinade and bring to a simmer over medium heat. Add the cornstarch-water mixture and cook for 1 minute or until slightly thickened. Brush sauce on the skewers and serve.