Saute sweet potato and onion in olive oil until the sweet potato is tender. Mix in the garlic, cumin, chili powder and salt and saute 1 more minute, or until fragrant. Remove from heat and mix in the black beans and red salsa.
Meanwhile, combine the tomato sauce, chipotle, garlic, tomato paste, water amd vegetabe broth base in a blender and blend until smooth.
Preheat oven to 425 F.
Grease the edges of a 9×13 inch baking dish. Then pour about ½ cup red sauce from the blender down the middle of the pan.
Spoon the black bean mixture into the corn tortillas, rolling them up and placing them seam side down into the sauce in the pan. Once all the tortillas are filled, pour the remaingin sauce over top and sprinkle with cheese.
Bake in the preheated oven for 20-25 minutes, or until the cheese is completely melted and the filling is bubbling.