In large saucepan, heat 2 tablespoons olive oil over medium heat. Add onions and mushrooms. Sauté until onions are translucent, approximately 4-5 minutes.
Reduce heat. Add garlic and sauté 1-2 minutes.
Turn heat to high. Add chicken broth. Bring to a boil.
Gradually add cornmeal while whisking continuously. Once all cornmeal is added, reduce heat to low.
Stir in sun dried tomato and basil. Cook and stir 10 minutes or until thick and creamy.
Remove from heat. Add butter and pepper. Stir until butter is melted.
Add ½ cup Parmesan cheese. Stir until cheese is melted.
Pour into 9 x 13 pan lined with parchment paper. Refrigerate to cool completely.
Sauté orange, yellow and red bell pepper strips in skillet using remaining 2 tablespoons olive oil. Once pepper strips are tender, add beans and stir until beans are warm. Remove from heat and cover to keep warm.
Once polenta is cool, cut into 6 pieces. Place on ungreased baking sheet. Broil 4 inches from heat for 5 minutes. Turn and broil 5-6 minutes longer or until heated through.
Top polenta slices with bell pepper and bean mixture. Sprinkle with ¼ cup Parmesan cheese.