Peel and chop the shallot. Pick the parsley leaves and chop them. Remove the skin of the duck leg then finely break up the flesh.
in a bowl, mix the duck flesh, the shallot and the parsley. Then roll the duck flesh in the brick pastry sheets to get 6 rolls.
Bring the red wine to a boil, then flambée it and reduce it to 3/4. At the same time reduce the balsamic vinegar, until it becomes sirupy.
Mix the reduced red wine, the reduced vinegar and the soy sauce. Then reduce it all until you get a slightly sirupy sauce, then add the very cold butter.
Peel the celeriac and cut it into thin strips with a mandoline (like tagliatelli).
In a pan of salted boiling water, cook the celeriac for 3 minutes, then drain it. Cook it in butter in a frying pan.
in another frying pan, cook the rolls until they are golden brown, then cut each roll into 2 pieces at an angle.
Arrange a layer of celery on the plates, then place the half duck rolls on top and finish with a drizzle of sauce. Garnish with chopped flat leafed parsley.