Sweet Potato Black Bean Taquitos

medium sweet potatoes (about 1 pound), peeled and cut into 1-inch cubes (about 4 cups)

chopped red onion

can black beans, rinsed and well drained

salsa

chili powder

cumin

garlic powder

salt

grated colby jack cheese

6- or 7-inch whole grain tortillas

olive oil or olive oil cooking spray

kosher salt

optional, for serving: guacamole, salsa, plain Greek yogurt or sour cream, etc.