Place cubed sweet potatoes in a medium saucepan with enough water to cover.
Bring to a boil; reduce heat and simmer, covered, 10 minutes. Drain.
Heat olive oil in a medium skillet. Add onions, garlic, and chiles. Cook, covered, over medium heat 5-7 minutes or until onions are tender.
Stir in cumin and coriander.
In a large bowl, mash the sweet potatoes, beans, cilantro, lime juice, and salt.
Stir in the onion mixture and one package of grated cheese.
Spoon approx. 1/2 cup of the mixture into each tortilla and roll. Place burritos seam side down in a lightly oiled baking dish. (You may need to divide the burritos into two baking dishes.)
Sprinkle with additional grated cheese.
Cover with foil and bake at 350 degrees for 30 minutes or until heated through.
Garnish with chopped cilantro, sour cream, and salsa as desired.