This recipe stands at the crossroads of east and west. It's inspired by the traditional Japanese soup shabu shabu, a broth containing meat, shiitake mushrooms, noodles and vegetables. Variations of it are found throughout Asia, in China and Vietnam.

If you don't have consommé, you can use bouillon cubes, one meat and one chicken, for each liter of water.

1. Place the ceps (porcini) in a bowl, add 500 ml (2 cups) water and soak for 30 minutes. Drain, strain the soaking liquid through a cloth and add it with the liter of consommé to a soup pot. 
2. Rub the meat on all sides with coarse salt and freshly ground pepper. Tie it up like a roast, keeping one end of the string long enough to tie to the handle of the pot, and add to the pot.
3. Add the peeled celery root. Cook for 25 minutes over low heat. 
4. Remove the meat with the string and let it rest at room temperature. 
5. Cook the vermicelli for 4 minutes in half the broth over low heat. Bring the remaining broth to a boil, add the ceps and reduce the heat; let infuse for 5 minutes. 

Finishing and presentation

1. Place the ceps and noodles with the meat (still tied) into a soup tureen. Cover and reserve while preparing the sauce. 
2. Crush the piece of celery root in a bowl with a fork; add the mustard and enough broth to form a sauce thick enough to coat a spoon. Pour into a sauce dish. 
3. Place the tureen on the table before your guests. Remove the meat and place it on a cutting board. Slice thinly. 
4. Place some vermicelli and ceps into 4 serving bowls; 
5. place the sliced meat on top with a sprinkling of coarse salt. 
6. Serve the sauce on the side and the remaining hot broth in bowls.