Combine the ingredients for the brine in a bowl. Rub the skin, flesh and cavity with the brine and put the breast uncovered in the refrigerator for 24 hours.
Put the puff pastry in the refrigerator if you have it in the freezer.
Turkey
Combine the wine and melted butter and set it aside.
Remove the skin and bones from the breast. You may use the bones for broth.
Inject the breast as much as possible with the injection liquid.
Vacuum seal the turkey and put in in a sous vide bath. Set the sous vide immersion cooker to 140 for 90 minutes, If your breast is frozen, add an additional 30 minutes,
When the turkey has finished cooking, remove it from the bag and use paper towels to thoroughly dry it.
Duxelles
Chop the mushrooms into very small pieces. A food processor does a great job with this.
Melt the butter in a saute pan and add the shallots in oil.
Add the mushrooms and saute for about 2 minutes.
Add the sherry and continue to saute until all the pieces of mushroom have browned and softened.
Remove the duxelles from the pan and let cool.
Pastry
Remove the pastry from the refrigeratror. Separate the two pieces. Roll the first one out to smooth it. Use the pastry lattice cutter and press down hard to make the cuts. Set the pastry aside.
Take the second piece and roll it out as well. It should be larger than your turkey breast.
Assembly
Preheat the oven to 400 °F (204 °C).
Line a sheet pan with parchment paper for easy clean up.
Lay the uncut piece of dough on the parchment.
Center the slightly cooled turkey on the uncut piece of dough. Brush the surface of the turkey with mustard.
Put the duxelles on top of the mustard and spread them around. Be generous.
Put the ham on top of the duxelles.
Bring the sides of the dough up and stretch it if necessary to cover the top of the breast.
Pinch the sides and close them with your fingers.
Take the lattice and lay it over the dough, Tuck it in lattice dough under and around the bundle. You may use an egg wash on the dough if you want to.
Put the turkey Wellington in the oven and roast for about 15 minutes. Check the dough. Roast until the dough is golden.
Remove the Wellington from the oven and let it rest for 10 minutes before slicing at the table.
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