48-Hour Short Rib:

1. Season your short rib with salt and pepper generously. Place into a vacuum bag and seal using a Foodsaver, ensuring there is no way for air to escape.
2. Preheat a sous vide water bath to 156ºF (69ºC). Once the water bath is hot, lower the short rib into the bath, cover the top of the bath with plastic wrap to keep the water from evaporating, and cook for 48 hours.  
3. After 48 hours remove the short rib from the water bath and place it in the refrigerator overnight. Once the ribs have fully chilled to firm, remove them from the bag and trim the meat from the bone into an evenly-shaped rectangle.
4. Set a 10-inch non-stick pan over medium-high heat. Once hot, sear the short rib on all sides for 1-2 minutes per side. Remove short rib from pan, brush on all sides with mustard and refrigerate 20-30 minutes. 

Spinach Crepes:

1. In a blender, combine flour, whole milk, and eggs. Blend on high until homogeneous. 
2. Add spinach to the blender and blend on high speed until the spinach is pureed into the batter as much as possible, about 30 seconds. 
3. Pass batter through a chinois or fine mesh strainer into a medium sized bowl. 
4. Heat a 10-inch non-stick pan over medium heat lightly greased with cooking spray, and once hot, add a 2-ounce ladle full of batter to the pan. Swirl to coat in one even ⅛ inch thin layer. Cook for 30-45 seconds or just until set, flip, and cook for an additional 30-45 seconds.
5. Remove the crepe from the pan and repeat. 2 crepes is enough for one Wellington. You can absolutely freeze this batter and use it again in the future.

Miso Bourbon Duxelle:

1. To a food processor, add all of the mushrooms and pulse until very finely chopped. 
2. Add butter to a 5-quart pot and heat over medium-high heat. Once melted, add your shallot, season lightly with salt, and cook until translucent, 1-2 minutes. 
3. Add the mushrooms and one sprig of rosemary and cook, while stirring occasionally, until there is no water remaining, 3-4 minutes.
4. Deglaze with Bourbon and cook until no liquid remains, being careful to watch that the Bourbon does not ignite if your heat is too high as it would be potentially more theatrical than you intend… but if it does ignite stay calm and let it continue until it burns out over medium heat.  
5. Cut the heat off and add garlic and, optionally, black truffle and stir together until thoroughly combined. Transfer to a large mixing bowl, discard the rosemary sprig, stir in miso and set aside to cool.

Assembly:

1. Preheat the oven to 400°F (205°C).
2. Cover your work surface with two large pieces of slightly overlapping plastic wrap. Place 2 crepes on top, slightly overlapping in the middle. 
3. Top with 4-6 slices of prosciutto, as evenly as possible, with minimal overlap, but ensuring they will stay together during the wrapping process. Evenly spread your duxelle into a square that completely covers the prosciutto.
4. Place your short rib at the base of your layers and tightly roll the crepe around the meat, using the plastic wrap to help guide the rolling. Tuck in the sides of the crepe and tightly seal it together with the plastic wrap. Wrap tightly and refrigerate for 15-20 minutes.
5. In a small bowl, whisk together the egg yolks and water until homogenous. Set egg wash aside.
6. Lightly dust a clean work surface with flour. Roll one sheet of puff pastry into a rectangle, about 10 x 14-inches and ¼-inch thick.
7. Remove the plastic wrap from the short rib log and place it at the base of the puff pastry. Roll the puff pastry over your short rib until just meeting the other end of the pastry, seal with egg wash and trim excess dough. Trim the sides of the dough so there is just about 1-inch of excess dough on either side, and pinch it together to seal tight. Ensure there are no holes in your wrap job. 
8. Wrap in plastic to close the edges completely and refrigerate for 10-15 minutes.
9. Remove the plastic wrap, place your Wellington on a parchment lined sheet pan and brush with egg wash until completely covered.
10. Optionally add a lattice crust to your Wellington by rolling out an additional sheet of puff pastry, cutting it with a lattice cutter, draping it over your Wellington, and brushing it with additional egg wash. 
11.  Season the top of your Wellington generously with flakey salt and bake for 20-25 minutes or until the pastry is golden brown and cooked through. Ensure the inside of your Wellington registers 140ºF (60ºC) internally before removing from the oven. We don’t need to worry about medium rare here because it's slow-cooked short rib.
12. Remove from the oven and let it rest for 5 minutes before slicing and serving.