STEP ONE

Add flour, eggs, sugar, salt, yeast and champagne to the food processor mixing bowl and start kneading using the dough hook. 

STEP TWO

Add the cubed cold butter and keep kneading until all the butter has been absorbed. 

STEP THREE

This results in a very thin dough so do not try to knead this by hand in case you don’t own a food processor. Wrap the dough in cling film and leave to rest in the fridge for 12 hours. 

STEP FOUR

Take the dough out of the fridge but let it acclimatise for 15 min-utes before you handle it again. Sprinkle the work surface with some flour, grease a rectangular loaf tin with melted butter and sprinkle with flour as well. 

STEP FIVE

Form the dough into a long brioche shape and put it in the baking tin. Leave the dough to prove for 2 hours. 

STEP SIX

Beat the egg for the egg wash and brush the top of the brioche with it. Bake the bread in a preheated oven at 180C for 20 min-utes. Remove the brioche from the baking tin and transfer to a wire rack to cool. 

STEP SEVEN

Cut 4 thick long slices and roast the slices of bread under a grill or in a toaster until nice and golden. 

STEP EIGHT

Put the sour cream in a mixing bowl and season with the horseradish purée and some salt and pepper. Transfer it into a plastic squeeze bottle and keep in the fridge. 

STEP NINE

Rinse the radishes, the Chioggia beet and the daikon and cut into thin slices. Put a slice of smoked salmon on every toast and finish with some thinly sliced radishes, daikon, Chioggia beet, some red mustard cress and the horseradish cream. 

Season the garnished toasts with freshly milled pepper.