Cook rice according to package instructions; set aside.
Meanwhile, heat oil in a large saucepan over medium. Add onions, garlic, jalapeno, and cumin; season with salt and pepper. Cook, stirring occasionally, until golden, 10 to 12 minutes. Add tomato paste, and cook, stirring, 1 minute.
Add beans and 1 1/2 cups water; bring to a boil, reduce heat to medium, and simmer, stirring occasionally, until thickened, 10 to 12 minutes. Add corn; cook to heat through, 2 to 3 minutes. Remove from heat; stir in scallions.
Heat tortillas according to package instructions; fill with rice, bean mixture, and cheese.
Assemble: Mound 1/4 cup rice, 3/4 cup bean mixture, and 1/4 cup cheese on one side of tortilla. Fold sides, and hold them in. Starting from filled end, holding sides in as you work, tightly roll into a bundle. Place on a baking sheet, seam side down, and prepare remaining burritos.
Serve immediately, with salsa and sour cream, if using, or wrap per freezing instructions.
Wrap individually in plastic and freeze up to 3 months.
To reheat from frozen:
Remove frozen burritos from plastic wrap. Place on a microwave-safe plate; microwave on high for 3 minutes. Transfer to baking sheet; bake at 450 degrees until crispy, about 10 minutes.
If only using a microwave, remove from plastic wrap, and place on a microwave-safe plate, covered with a microwave safe bowl. Defrost at high power for 3 to 4 minutes; uncover, and microwave on high 3 to 4 minutes longer.
If only using oven, remove burritos from plastic wrap; rewrap individually in aluminum foil. Place on a baking sheet; bake at 450 degrees for 40 minutes. Remove foil, and bake to crisp, 5 to 10 minutes. (To reheat defrosted burritos, remove any wrapping and bake for 10 minutes).