In a medium pot, add potatoes and cover with water about 1 inch above the potatoes. Place the pot on a burner on high and boil until tender, about 10 minutes. Drain, and set aside.
In a large cast iron skillet over medium heat, combine the chorizo and onion. Sauté, stirring very frequently, until sausage is cooked through and onion is soft, about 10 minutes.
Add the sliced mushrooms and cook for about 5-7 minutes more until the mushrooms have cooked down.
Add the potatoes and stir to combine. Let the entire mixture cook for about 5 minutes more until the potatoes are just golden brown.
Reduce the heat to low and set aside.
Wrap tortillas in a warm, damp kitchen towel, put them on a microwave-safe plate dish, and warm them in the microwave for 4 minutes.
Top each tortilla with the mushroom, potato chorizo mixture and any desired toppings and serve immediately.