Cut pork loin vertically down center. Open flat, like a book. Cut thick pieces and keep opening until pork is flat. Pound to flatten.
Heat olive oil over medium heat. Add onion, and sauté 10 minutes. Add spinach and sauté until liquid is evaporated. Add feta, lemon and herbs. Place spinach stuffing into center of pork. Close pork over spinach filling and tie with kitchen string. Sprinkle outside of pork with garlic powder, salt and pepper.
Place pork in roasting pan, and place in oven and bake for 45 minutes. Remove from oven and drizzle with sorghum. Bake 25 minutes longer.
