2 Tbs. extra-virgin olive oil
1 cup diced yellow onion
3 garlic cloves, minced
1 cup finely chopped cremini mushrooms
1 cup finely chopped peeled carrots
1 cup finely chopped celery
1 cup finely chopped cored Brussels sprouts
2 bay leaves
1 cup vegetable stock
2 12-oz. packets of crumbled beef-less ground beef (Trader Joe’s brand preferred)
1 Tbs. Worcestershire sauce
1 Tbs. soy sauce
Mashed potatoes, for topping (recipe below)
2 lbs. Yukon Gold potatoes, peeled and cut into 2-inch cubes
2 tsp. kosher salt
4 oz. salted butter, cut into 1-inch cubes
1/2 cup sour cream
1/4 cup mayonnaise
1 Tbs. whole grain mustard (optional)
1/2 cup warmed whole milk
Kosher salt and pepper, to taste
14- by 9- by 2-inch baking dish
Heat the olive oil in a large sauté pan over medium heat. Add the onions and cook, stirring for about four minutes, until translucent. Add the garlic and stir for one minute.
Add all the other vegetables, the bay leaves, and 1/2 cup of the vegetable stock. Keep the leftover stock on hand, adding as needed to keep the mixture from drying out while cooking.
Cook the mixture for approximately eight minutes, or until the vegetables are al dente. Add the beef-less ground beef, Worcestershire sauce, and soy sauce. Stir for two to three minutes, or until the mixture is heated through. Transfer to the baking dish and smooth out in an even layer.
For the mashed potatoes:
Place the potatoes in a large bowl of cold water and soak them for one hour to reduce the starch. Drain in a colander.
Combine the salt and eight cups of water in a large pot and stir to ensure the salt dissolves completely. Add the drained potatoes, cover the pot, and bring to a boil over high heat, stirring occasionally. Once boiling, reduce the heat to medium-high and cook the potatoes for about 10 minutes, until they are soft enough to split with a fork.
Drain the potatoes in a colander, then return them to the pot. Add butter, sour cream, mayonnaise, and mustard (if using), and let the butter start to melt. Slowly stream in the warm milk and simultaneously mash the potatoes with a hand masher just until smooth. If mashed too long, the potatoes can get clumpy. Season them with salt and pepper to taste.
Position a rack in the middle of the oven and preheat to 400°F.
Spoon the mashed potatoes on top of the meat-less mixture in the baking dish, then gently rake the top of the mashed potatoes with a fork to make a grid. Cover the baking dish with foil and bake the pie for 40 minutes. Uncover it, then broil for four to five minutes, until the tops of the potatoes turn golden brown. Serve immediately.
You may refrigerate the pie for up to five days or freeze it for up to six weeks. Uncover and let it reach room temperature before reheating.