Heat butter/oil in nonstick fry pan or on grill. Cook potatoes according to package directions; keep warm.
In separate spray-coated pan or on griddle, cook and scramble eggs until soft. Stir in chorizo. Cook eggs until firm throughout with no visible liquid egg remaining.
Portion 6 oz. potatoes and about ¾ cup eggs into each of 12 (2-cup) individual serving bowls. Top each bowl with 1½ oz. each cheese and avocado. Add 1 oz. sour cream and ¼ cup ranchero sauce, if desired.
Note: Do not let uncooked egg mixture remain at room temperature for longer than one hour (including preparation and service time).
*If using frozen or liquid whole egg product.