1 litre salt water (5% salt)
Bincho-tan Japanese charcoal
4 -ounce portion beef rump
1 kilogram beef
100 grams shallots, sliced
150 milliliters port wine
900 milliliters Red wine
5 grams kuzu (Japanese arrowroot) powder
8 spinach roots (the base of a bunch of spinach leaves)
Grated yuzu zest
Minced green onion
For the Sumi of Shimonita Negi (Leek Charcoal):
Soak the leeks in salt water for 30 minutes, dry, and grill over the bincho-tan (or all natural charcoal) slowly until completely charred and all the moisture is cooked out. When the leeks are completely dehydrated, put into a dehydrator to dry until hard. Put them in a blender until completely pulverized in powder form.
For the Beef:
Quickly sear the meat, being sure to keep the internal temperature below 60°C/140°F. Preheat the butter and olive oil to 80°C/176°F, and cook the beef in the butter-oil until the center of the meat reaches 54°C/130°F.
For the Red Wine Beef Jus:
Dice the beef into 3-centimeter cubes and cook in the olive oil; sauté the shallots in a separate sauté pan; and heat the red wine and Port wine in another pot until the alcohol is cooked off and then cool. Combine all the ingredients a stainless steel pot, and put them in a steam convection oven for 10 hours at 95°C/203°F.
Remove the pot from the oven and cool to room temperature. Strain once to remove the solids, and then again through cheesecloth or a filter to filter out the impurities. Simmer and reduce until there is about 200 milliliters of sauce. Add kuzu powder while whisking and season with salt.
To Assemble and Serve:
Blanch the spinach roots in salted water. Add the grated yuzu zest, minced green onion, and salt to the leek ash to taste. Completely cover the beef with the leek ash powder. Present the whole beef portion to the table; then slice in the kitchen and serve with two spinach roots and a spoonful of red wine beef jus.