Preheat a sauté pan over medium heat.
Drizzle 4 tbsp. Oil and the butter, crack the eggs in the pan.
Season well and cook for 2 minutes until the white are set and the egg yolk is still runny. Add the butter and let the butter baste the eggs for a further 2 minutes or so until the eggs are cooked to your liking. If you like the eggs been fully cooked, cover with a lid to allow the egg yolk for a fully cooked egg yolk.
Toast the brown bread and butter. add a thin layer of mustard and top with the eggs.
Serve with some salad leaves.