Heat oil in a medium skillet over medium heat. Add onion and sauté until golden, about 5 minutes. Add garlic and pepper strips; cook and stir 1 minute. Remove from heat.
Remove stems from mushrooms and wipe mushroom caps clean with a damp paper towel; place on a baking sheet.
Combine tomato paste, TABASCO® Chipotle Sauce, and water in a small bowl and mix well; spread evenly over the underside of each mushroom cap, then top with onion and bell pepper mixture and sprinkle with salt and pepper.
Bake in a 450°F oven for 5 minutes; sprinkle with cheese and bake 1 to 2 minutes longer until cheese is melted. Sprinkle with cilantro and serve immediately.
Makes 6 servings.