1. In a small dry skillet over medium heat, toast coriander and cumin seeds until aromatic, about 1-2 minutes. Remove from skillet. Crush seeds using a spice grinder or mortar and pestle; set aside.
2. Sprinkle pork with salt and pepper. In a Dutch oven, brown roast in oil on all sides. Remove and set aside. Add tomatillos and onion to the pan; sauté until tomatillos are tender and lightly charred. Add the garlic and crushed spices; cook 1 minute longer.
3. Add wine, stir to deglaze pan. Stir in broth and return roast to pan. Bring to a boil.
4. Remove pan from stovetop. Cover and bake at 350 F for 3 to 3-1/2 hours or until pork is tender. Slice or shred pork. Keep warm until ready to serve.
5. To make polenta: In a large heavy saucepan, bring chicken broth to a full boil. Reduce heat to a gentle boil. Slowly whisk in cornmeal. Cook, stirring constantly with a wooden spoon for 15 to 20 minutes or until polenta is thick and pulls away cleanly from the sides of the pan.
6. Serve pork and sauce over the polenta. Eat immediately. Makes 6 servings.