First, prepare the sweet potato, which needs the longest time to cook.
Chop about one half a cup of sweet potato into bite-sized cubes.
Spread parchment paper or greased tinfoil onto a baking sheet.
Bake the sweet potato cubes at 350 degrees until tender, for about twenty minutes.
While the potato cooks, simmer half a cup of dry green lentils in 1.5 cups of water. The lentils will double or triple in size. Rinse and drain any excess water once the lentils are soft.
Once the potatoes and lentils are cooking, dice the rest of the vegetables and set aside.
Finely mince the 8 oz of mushrooms.
Dice the half cup of celery and half cup of white onion into pieces no larger than an almond.
Assemble the spices and sauces you will use to sauté the vegetables.
Use two tablespoons of tomato paste, one tablespoon of minced garlic, one tablespoon of vegan Worcestershire sauce (such as Annie's brand), one tablespoon of poultry spice blend (also sold as chicken grilling spice blend), three tablespoons of nutritional yeast, and a pinch of black pepper.
Add one tablespoon of ground flaxseed and stir everything together to give the flaxseed a chance to soak.
Sidenote: almost all Worcestershire sauce brands use anchovies. Check the label for fishy ingredients before buying!
Poultry spice contains no meat. It is a dry blend of garlic, salt, citrus, pepper, parsley, bell pepper, and paprika.
Begin sautéing the celery, onions, and mushrooms in a small amount of oil or vegetable broth.
Stir in one cup of cooked lentils and the spices you assembled earlier.
Stir in the baked sweet potato pieces.
Continue to saute until the celery and onion have released most of their water, and the mixture becomes fairly dry. If the filling releases too much water while cooking inside the pie, the pie bottom will be soggy.
Increase the oven temperature to 425°F to prepare to bake the pie.
Line a 9"x5" baking pan with parchment paper.
Line again with a sheet of vegan puff pastry.
If it's difficult to hold in place, you can temporarily prop it up using wet vegetables, such as baby carrots.
It's quite important to thaw the puff pastry in the fridge overnight. If you try to quickly thaw the puff pastry in a warm environment, the folded layers will fuse together. If this happens, you can recover the shape by rolling it out with a rolling pin on a floured surface, which can be quite a hassle! Be sure to check for bits of packaging in the warm dough.
Mash the cooked filling in a large mixing bowl. Stir in 3/4 cup of crushed walnuts, 1/2 cup of panko breadcrumbs, and three tablespoons of flour.
The mixture should have a sticky consistency, so that it holds together in a ball if you squeeze it as shown. If it is too loose, stir in a bit more flour and try again.
Stuff the filling snuggly into the pastry-lined pan. Begin by filling the corners, then pat the rest firmly in place. Unlike watery pies or cake batter, this filling will not settle much, so make it flat on top.
Top the pie with a second layer of puff pastry. Lay the new layer flat over the pan. Trip off any overhang using kitchen scissors. Pinch the edges of the two pastry sheets together so that there is a complete seal. Roll the pinched layers towards the center of the pan to make a puffy border.
It's important to cut vents in the pie top, in order to allow steam to escape without deforming the pie. Use whatever design you like!
Bake the pie at 425°F until the top appears golden brown. This takes about 35 minutes. This recipe is better to underbake than to overbake, so check it frequently!
Once baked, gently turn the pie and pan upside down, as if making a sand castle. You should be able to remove the parchment paper easily, as this sturdy wellington holds its shape.
Slice with a large bread knife and serve!
This recipe pairs will with mashed potatoes and gravy for a holiday meal.