to make the filling:

1. Preheat a medium-sized, wide pan over medium heat. (I used enameled cast iron.)
2. Add the vegan butter to the pan and allow to melt.
3. Add the carrots and saute until slightly soft, about 2 minutes.
4. Add the celery and saute for about 3 minutes.
5. Add the onion and saute for about 5 minutes.
6. Add the sage and thyme and stir. Allow to saute for 2 minutes more.
7. Add the lentils, and stir for one minute.
8. Add the vegan bouillon, and stir until combined. Allow to saute for one minute more.
9. Transfer the mixture to a large prep bowl, scraping everything off the pan.
10. Return the pan to the stovetop and add the olive oil.
11. Add the ground vegan sausage to the pan. Allow to slightly brown for about 3 minutes.
12. Transfer it to the large prep bowl, stir, then fold in the panko crumbs.
13. If you’d like to cool down the mixture right away, transfer it to a baking sheet and set aside.

to make the duxelles:

1. Preheat a large pot or pan (I used an enameled cast iron pan) over medium-low heat.
2. Add the plant-based butter to the pan and allow to melt.
3. Add in the shallots and saute until softened, for about 3 minutes.
4. Add the garlic, stirring occasionally for about 3 minutes.
5. Increase the heat to medium and add in the sage and thyme. 
6. Add the mushrooms, and stir to coat with the shallots, garlic, and herbs. Allow the mushrooms to soften for about 10 minutes while stirring occasionally.
7. Once most of the liquid has been evaporated and the mushrooms are starting to develop a little color, increase the heat to medium-high.
8. After about one minute, deglaze the pan with the wine. Remove from the heat once all of the moisture has evaporated. 
9. Set aside to cool to room temperature.

to assemble the vegan Wellington:

1. Preheat oven to 425.
2. Dust your work surface with a little flour.
3. Gently unroll the pastry sheet once it’s pliable.
4. Half the room-temperature duxelles into two portions.
5. Place some of the duxelles into a rectangular shape in the center of the puff pastry.
6. Divide the room-temperature filling into two portions.
7. Mold the filling into a small rectangle-shaped loaf, and place it on top of the duxelles.
8. Scatter the rest of duxelles over the top of the filling. 
9. Referring to the photos in the post, make 1-inch cuts in a diagonal line on both sides of the pastry.
10. There should be enough space at the top and bottom to fold a little flap over the top and bottom of the filling. 
11. You can cut away the triangle shapes in each corner, but save them in case you need to patch any spots in your Wellington once braided.
12. Referring again to the photos, fold the bottom flaps over the top and bottom. Then, start braiding from the top, using a criss-cross pattern. You may need to slightly and gently pull on the braiding strands before folding them across to ensure they are long enough to cover the sides.
13. The Wellington should have narrow gaps between the braids. This allows steam to escape while baking.
14. Oil the bottom of a cast iron pan or baking sheet. Pick the Wellington up with a large spatula and transfer to the pan.
15. Brush the tops and all over with the melted vegan butter.
16. Repeat the process with the remaining filling, duxelles, and pastry sheet.
17. Bake for 20 minutes. Remove from the oven and brush the top again with more vegan butter. Bake for an additional 5-10 minutes, or until the tops are golden brown.

to serve:

1. Let the vegan Wellingtons rest for a few minutes before cutting. Serve with mashed potatoes, vegan gravy, and vegetables for a festive holiday dinner!