Spray large skillet with cooking spray; heat over medium heat until hot. Cook onion and potato until onion is tender and potatoes are browned, about 5 minutes. Stir in chorizo and cook 2 minutes longer. Remove from heat; stir in the cheese and cilantro. Season to taste with salt and pepper.
Heat tortillas one at a time in skillet untill softened. Spoon about 1/2 cup filling mixture onto each tortilla and fold in half. Spray large skillet with cooking spray; heat over medium heat until hot. Saute tacos until lightly browned about 1 to 2 minutes on each side. Serve with salsa and sour cream.