Heat a non-stick skillet over medium heat and add the butter or cooking oil. Let it melt and coat the pan evenly.
While the pan heats up, gently make a hole in the center of your bread slice using a round cookie cutter or the rim of a glass. Place the bread in the pan.
Crack the egg into a small bowl, taking care not to break the yolk. Slide the egg gently into the hole in the bread.
Allow the egg to cook undisturbed for about 2-3 minutes until the white is set but the yolk is still runny.
Carefully flip the bread and egg together using a spatula, and cook for an additional 1-2 minutes until the yolk reaches your desired level of doneness.
Slide the cooked egg-topped toast onto a plate.
Sprinkle the chopped cilantro evenly over the egg.
Drizzle the lime juice over the cilantro and egg. The lime adds a tangy brightness that pairs perfectly with the richness of the yolk.
Season with a pinch of salt and a dash of pepper to taste.