With a fork, poke holes in the sweet potatoes. Wrap the sweet potatoes with paper towel, set one at a time on a microwavable plate and microwave each individually for 5-8 minutes, or until softened throughout.
Meanwhile, in a shallow dish, whisk together the egg and lemon juice.
In a separate shallow dish, combine the cornmeal, flour, onion powder, garlic powder, chili powder, and smoked paprika.
Coat cod pieces with the egg mixture and then the cornmeal mixture.
In a large skillet, melt 1 tablespoon butter. Add the oil to the skillet. Carefully add the fish pieces to the skillet and allow to cook 4-6 minutes on each side, or until the outside is golden brown.
Once the sweet potatoes are cooked, cut them in half. Use a fork to mash the sweet potatoes. Place 1 teaspoon butter on each sweet potato half. Allow butter to melt, and mix the melted butter in with the mashed sweet potato.
Sprinkle with salt and pepper, to taste.
Serve 3 pieces cornmeal crusted cod with 1/2 of a sweet potato. We also served ours with canned green beans.