Crumble chorizo in a large nonstick skillet and place over medium heat. Cook, stirring frequently, for about 5 minutes or until sausage is half cooked.
Increase heat to medium-high. Add onion and mushrooms; continue to cook, stirring almost constantly, for about 3 minutes or until vegetables begin to soften.
Sprinkle potatoes into skillet; cook, stirring frequently, for 10 to 15 minutes or until potatoes are soft. Season to taste with salt. Transfer mixture into a bowl and top with cilantro. Serve in tortillas with Roasted Tomatillo Salsa.