• Remove your puff pastry from the freezer and let it thaw for about 45 minutes.

Make caramelized onions

• While the pastry is warming, peel and slice 2 onions into long, thin slices, then toss them into a frying pan with 2 tbsp of olive oil and 1/4 tsp. salt.  Cook the onions uncovered on low, stirring occasionally, for 30-40 minutes, until they turn a light brown and become sweet. (Add a sprinkle of water to the onions as they are cooking if they start to look dry.)

Make mushroom "bacon"

• Slice a large portabella mushroom into thin slices and fry in 1 tbsp of neutral-flavored oil.  Sprinkle with salt and liquid smoke, then cook for about 7-8 minutes per side, until thoroughly cooked.

Make the tofu filling (or other fillings of choice)

• Crumble drained, pressed, extra-firm, or high-protein tofu into a food processor. Add the vegan broth, poultry seasoning, nutritional yeast, soy sauce, salt, and pepper to the food processor, then blend until combined.
• (If not using the tofu method, use 12 oz. of vegan ground beef, or see further instructions in the variation section of this post.)

Assemble your wellington

• Once you have prepped all your ingredients, be sure to preheat your oven to 400°F. (You need it to go into a preheated hot oven to achieve a great puffy rise.)
• Place 1 rectangle of pastry puff on a cookie sheet that has edges.
• Add a layer of caramelized onions down the center of the pastry puff, leaving about 3 inches (7.5 cm) on both sides and about 1/2 inch (1.25 cm) on the top and bottom.
• Layer the portobello mushroom bacon (or other vegan bacon, if you choose) on top of the onions, slightly overlapping the mushroom slices.
• Top with a layer of seasoned tofu (or vegan beef, lentil loaf mixture, or vegan meatball mixture) that is about 3 inches (7.5 cm) wide, covering the onions and mushrooms, and about 1 1/2 inches (3.75 cm) high.
• Cut diagonal lines in the puff pastry at a 45-degree angle, starting at the bottom corners.  Cut another line every inch until you reach 1/2 inch from the top.
• Fold the top and bottom triangles of the pastry in and over the filling. Then fold the strips over one another, alternating sides, starting at the top and working down to form a woven, braided look.
• Brush your Wellington with a little melted vegan butter or aquafaba (the liquid from a can of chickpeas) to give it a little shine.
• Bake the wellington at 400°F for 35 minutes, or until the pastry has puffed and turned golden brown.
• Allow it to cool for about 10 minutes before slicing and serving.