Heat a small non-stick skillet over medium heat. Add the olive oil.
Crumble the feta cheese into the pan in a circle shape, leaving a hole in the center. Cook for 1-2 minutes until bubbling and edges start to gold.
Crack the egg gently into the center of the cheese ring.
Season with black pepper and red pepper flakes.
Cover the pan with a lid. Reduce heat slightly to medium-low and cook for 2-3 minutes until the whites are set but the yolk is still runny.
Serve immediately on a plate or over toast. If using a tortilla, place it over the egg before flipping to serve taco-style.