Preheat your oven to 375 degrees F. In a 10-12 inch ovensafe skillet, sauté the onion and jalapeño in oil until soft. Add the chili powder, garlic and oregano and sauté until fragrant. Mix in the pinto beans, tomatoes and corn and let simmer gently, stirring occasionally, until most of the liquid has boiled off. Salt to taste.
Meanwhile, microwave the polenta and water in a covered bowl until soft and the water is absorbed, about 8 minutes, stirring halfway through. Lightly salt and add oil or butter. Gently spread the cooled polenta over the tamale pie filling and bake for 20-30 minutes, until he top is slightly brown. Enjoy!