Cook chorizo and onions in medium ovenproof skillet on medium heat 8 min. or until chorizo is done, stirring frequently. Add potatoes and chiles; cook 2 min., stirring occasionally. Remove from heat. Stir in 1/2 cup cheese; spread to form even layer in skillet.
Whisk eggs and sour cream until well blended; pour over chorizo mixture. Top with remaining cheese.
Bake 25 min. or until center is set. Serve topped with salsa.