1. Place the butter, horseradish, Dijon mustard, shallots, salt and pepper in the stainless-steel bowl of an electric mixer fitted with a paddle attachment. Mix on low speed until blended.
2. Place 454 g portions of butter on sheets of parchment paper and roll into 2” cylinders.
3. Wrap the rolls in plastic to preserve their flavour. Refrigerate until needed.
1. Make the Dijon shallot butter according to recipe instructions and slice the refrigerated butter into 1"-thick pieces. Place in a stainless-steel mixing bowl. Cover with film wrap. Allow it to come to room temperature so it’s spreadable.
2. Remove all of the fat and silverskin from the strip loin. Wrap the meat in film wrap and place in the freezer for about 1 hour or until it is firm enough to slice.
3. Place the strip loin on an electric slicer with the best end down so it can be sliced against the grain. With the slicer at the 7½ setting, slice into 10 28-g slices. Lay the slices on a parchment-lined sheet pan in a single layer.
4. Lay a piece of beef out flat on a film-wrapped, rimless metal baking pan. When assembling, don’t press down on the layers. To make layers, spread a portion of the Dijon shallot butter over the beef to cover evenly. Carefully lay a second piece of beef on top of the first layer of butter. Once again, spread 28 g of butter on top of the beef. Repeat with the other 8 beef slices to create a stack with 9 layers of butter and 10 layers of beef. Cover with film wrap and refrigerate for 24 hours.
5. Slice the bread into 14 g pieces widthwise. Place side by side on a parchment-lined sheet pan. Place in a heated 148°C (300°F) convection oven for 6-7 minutes or until they just begin to brown. Lower the temperature to 107°C (225°F). Cook another 8-10 minutes or until crunchy. Allow to cool. Place in a storage container. Cover until needed.
To prepare à la carte:
Slice 3 pieces of the layered meat and butter widthwise a little less than 21 g so the three pieces weigh about 56 g together. Place the slices on the front of a chilled serving plate so they are not touching. Sprinkle coarse black pepper and the fleur de sel to taste over the carpaccio butter. Place 7 bread rounds on the plate next to the carpaccio butter.