For the brioche-buns warm the milk lukewarm. Sift 500 g flour into a mixing bowl. Add 1 pinch of salt. Stir yeast with sugar until liquid. Add yeast, milk and 3 eggs to the flour and knead with the dough hooks of the mixer for about 5 minutes. Add butter and knead until smooth. Cover and leave to rise for about 1 hour.
Line baking tray with baking paper. Knead the dough again and form a roll (approx. 40 cm long). Cut into 8 pieces and form into balls. Distribute on the baking tray. Cover and leave to rise again in a warm place for about 30 minutes.
Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Whisk egg yolk and 1 tbsp. water. Spread a thin layer of Buns. Sprinkle with sesame seeds. Bake in a hot oven for about 20 minutes. Take out and let cool down.
In the meantime, mix the salad cream and mustard for the topping. Cut the gherkins lengthwise into thin slices. Clean and wash the salad, shake dry, halve the leaves. Heat 1 teaspoon butter in two pans. Fry 4 eggs in each pan to make fried eggs. Season with salt and pepper.
Cutting open buns. Spread with mustard cream. Alternately cover the undersides with lettuce, roast beef, cucumber and one fried egg each. Place topsides on top.
To defrost, simply bake the brioche-buns in the oven at 220 °C for 6-10 minutes.