Slice bread and toast for serving. Have all other ingredients at the ready, as this recipe comes together quickly!
Melt butter in a pan over medium heat. Crack eggs into pan.
Salt and pepper eggs to taste. Continue frying until whites crisp on the edges and yolk is just set but runny in the center (or according to your preference).
Transfer eggs to serving plates along with toasted bread. Return pan to heat and add vinegar. Swirl the vinegar with the leftover butter until reduced by half. Remove from heat.
Spoon vinegar reduction over eggs. Sop up yolk and sauce with bread, and enjoy!