1. Heat oil in a Dutch oven over medium heat. Add onion to pan; cook 8 minutes or until tender, stirring occasionally. Stir in broth, corn, and garlic; bring to a boil. Cover, reduce heat, and simmer 5 minutes. Slowly add polenta, stirring with a whisk until polenta is thick (about 5 minutes). Add cheese, stirring to melt. Stir in salt and pepper. Remove from heat; sprinkle with tomato and basil. Serve immediately.