It came true. I wanted to reproduce smoked tongue since I tasted it for the first time in Tokyo more than two years ago. Now I know how to make a decent version at home with kitchen tools I have: sous vide and a stovetop smoker.
Most likely the original recipe included marinating and either cold or slow hot smoking. My recipe is very lazy in comparison, simplified, and surprisingly good.
If using smaller watermelon radishes (D 2 1/2″), you will need 2-3 slices fo every roll. With larger radish, you need only one slice per roll. Watermelon radish makes these rolls stunning visually. Asian Purple radish/daikon is another good option. If neither available or you don’t care for presentation, substitute it with white daikon.
Vacuum pack beef tongue and cook sous vide for 12 hours, 155F. Cool down in an ice bath and refrigerate packed.
Unpack and cut the tongue into four pieces to fit inside the smoker. Close a lid and place over high heat for 25 minutes. Turn off the heat and keep the smoker closed for another 30 minutes to continue slow cooking. When it is down to room temperature, transfer the smoked tongue into a sealed container and refrigerate for at least 2 hours before slicing. Slice it 1/16" thin before assembling rolls.
Wash and peel radishes. Slice them 1/16" thin and julienne half of slices. Wash and quarter cucumber, cut off seeds. Slice 1/8" thin and julienne it. Wash and pick cilantro.
Make rolls as shown in the picture. Sprinkle some salt on tongue slices and add a dab of mayo. If necessary, secure rolls with skewers.