To make polenta, bring 3 cups of water to boil in a large pan. Whisk in 1 cup of cornmeal. Turn the heat down to a bare simmer and cook for 15 minutes, whisking occasionally. Once thickened, whisk in to the polenta: 2 Tablespoons butter, 1 Tablespoon of granulated sugar, 1 teaspoon of salt and cracked black pepper. Cook for an additional few minutes until the butter is fully melted. Remove from heat.
In a large bowl mix together 2 cans of drained pinto beans, 1 can of drained black beans, 1 cup of fresh or frozen corn, 1 - 16 oz. jar of thick salsa, 1 - 15 oz. can of drained diced tomatoes, 1/2 cup chopped cilantro, 1/3 cup chopped red onion, 2 minced garlic cloves, 2 T. fresh lime juice, 2 tsp. cumin, 1 tsp. oregano and 1/2 tsp. salt. Set aside.
Spread the polenta at the bottom of a well-greased 13x9 baking dish. Next, spread your bean mixture onto the polenta and then top with 2 cups of shredded Monterey Jack cheese.
To Bake Right Away: Bake uncovered 350˚ F for 45 minutes or until the internal temperature reaches 160˚ F. Let cool for 10 minutes before serving.To Freeze: Cover with heavy-duty foil, label, and freeze. From freezer to oven, bake for 45 minutes in a 375˚ F oven or until the cheese is golden and sides are bubbling. Cool for 10 minutes before serving.