* Percent Daily Values are based on a 2000 calorie diet.
Preheat your oven to 400º F.
Remove the stems from your portobello mushrooms and coarsely chop the stems. Place the mushroom caps, stem side up, on a baking sheet.
Spray a large nonstick skillet with cooking spray and place over medium heat. Add your onions to the skillet and cook for about 1 minute, or until the onions become soft. Add your garlic, stirring them in with the onions for about 20 seconds. Add your chopped mushroom stems and cook for another 2 minutes, occasionally stirring. Your mushroom stems should become soft.
In a large bowl add the ingredients from the skillet. Stir in the beans, serrano pepper, basil, Worcestershire, oregano, salt, and pepper.
Add half of your mushroom mixture to a food processor and process until smooth before mixing it in with the remaining mushroom mixture. Stir your corn into the mixture.
Stuff the portobello mushroom caps with the filling and loosely cover with tin foil. Bank for 15 minutes and then remove the foil and continue to bake for another 5 minutes. Your mushrooms should be browned and sizzling.
Cooking times will vary if you increase or decrease the default number of servings. Cook all meat, poultry, fish and eggs thoroughly.