Beat eggs, Hellmann's® or Best Foods® Real Mayonnaise, parsley and black pepper in small bowl with wire whisk; set aside.
Heat olive oil in large nonstick skillet and lightly brown chorizo over medium heat, stirring occasionally. Add potatoes and onion and cook, stirring gently, until onions are almost tender, about 5 minutes.
Add egg mixture. Cook over low heat, lifting set edges of omelet with spatula and tilting pan to allow uncooked mixture to flow to bottom. Cover and cook until omelet is set, about 5 minutes. Garnish, if desired, with additional chopped parsley.