Prep peppers: Cut ¼-inch from tops of bell peppers and remove the stem, ribs and seeds. Fill a large baking dish with 1/2-inch of water.Place peppers cut-side down in the water and bake for 20 minutes.
Filling: Heat oil in a 12-inch skillet over medium-high heat. Add onion and cook until softened, about 5 minutes. Add garlic and cook for 30 seconds. Add corn, beans, diced tomatoes, green onions, chili powder, cumin, salt, and pepper. Stir until corn and beans are heated through, about 5 minutes. Remove skillet from heat and stir in rice, 1 cup cheese, and cilantro. Stir to combine. Taste and add additional seasonings, if needed.
Stuff peppers: Remove peppers from oven and drain water from dish. Divide the mixture evenly between the peppers, then top with remaining cheese.
Bake again: Return to oven for 10-15 more minutes, until peppers are tender and cheese is melted. Store leftover peppers in the refrigerator, covered for 4-5 days.
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Notes
Peppers: Choose big, round bell peppers that sit flat. Or lay them on the side and cut a small piece from the top, horizontally. Red, orange and yellow peppers will be sweeter than green.Taco Seasoning: To use your own spices, use 1 Tablespoon chili powder, 2 teaspoons ground cumin, 1/2 teaspoon paprika, 1/4 teaspoon garlic powder and oregano.Add more Protein: Add one pound of cooked ground turkey to the filling.Make-ahead Instructions: Stuffed peppers can be assembled 1-2 days ahead of time, stored in the fridge until baking.Freezing Instructions: Freeze the filling for up to 3 months. Allow to thaw before stuffing peppers.