Preheat the oven to 400 degrees Fahrenheit and line a large baking sheet with parchment paper for easy cleanup.
Peel the sweet potatoes and then cube into 1 inch cubes, toss in bowl and coat lightly with olive oil. Place the sweet potatoes on the baking sheet. Bake until they’re tender and cooked through, about 20 minutes. Leave the oven on, since we’ll bake the assembled enchiladas soon (no temperature adjustments necessary).
Meanwhile, pour enough salsa verde into a 9 by 13-inchbaking dish to lightly cover the bottom (about 1/2 cup). In a medium mixing bowl, combine all of the remaining filling ingredients.
Ina medium mixing bowl lightly mash the sweet potatoes with a potato masher. Then combine all of the remaining filling ingredients.
Wrap the stack of tortillas in a clean tea towel and then warmup your tortillas, in a microwave so they don’t break when you bend them.
Working with one tortilla at a time, spread about 1/4 cup filling down the center each tortilla, then wrap both sides over the filling and place it in your baking dish. Repeat for all of the tortillas.
Top with the remaining salsa verde and cheese. Bake for 25 to 35 minutes, until sauce is bubbling and the cheese is lightly golden.
Let the enchiladas cool for about 5 minutes. Whisk the sour cream and water together to make a drizzly sour cream sauce. Drizzle it back and forth over the enchiladas, then top them with cilantro and red onion. Serve.