Combine rice, southwest seasoning and water in a saucepan, and bring to a boil. Reduce heat to low, cover, and simmer for 35 to 40 minutes, or until tender. Remove from heat, and cool.
Place black beans and pinto beans into a colander or strainer, and rinse. Add corn, onion, spices and salsa, and toss to mix. Transfer to a large bowl, and mix in rice and cheese. Divide the mixture evenly among the tortillas, and roll up.
(Makes about 20 burritos)
To Freeze: Freeze in freezer safe container.
To Reheat: Heat in microwave.