In a medium saucepan, bring 2 1/2 cups water to a boil. Meanwhile, in a large skillet, heat 2 tablespoons olive oil over high heat, swirling to coat the pan. Add the pork to the skillet in an even layer and season with the chili powder, 1/2 teaspoon salt and 1/4 teaspoon pepper. Cook, stirring, until just brown all over, 2 to 3 minutes. Transfer the pork and any juices to a plate. Add the remaining 1 tablespoon olive oil, the bell pepper and finely chopped scallions to the skillet and cook, stirring, until crisp-tender, about 2 minutes.
Whisk the polenta and 1/4 teaspoon each salt and pepper into the boiling water and cook, whisking, for 2 minutes. Lower the heat to low, whisk in the cream, then stir in the cheese; cover to keep warm.
Add the corn to the bell pepper mixture and cook for 1 minute. Return the pork and any juices to the skillet and cook, stirring, until heated through, about 1 minute. Stir in the sliced scallions. Serve with the polenta.