Can I make this recipe ahead of time?

Name: Elegant Mushroom Wellington
Prep time: 90 min
Cook time: 50 min
Total time: 170 min
Ingredients: 4 medium portobello mushrooms (each about 3 inches wide (8 to 10 ounces total)); 1 tablespoon extra virgin olive oil; kosher salt and black pepper; 2 pounds mixed mushrooms (such as baby bella (cremini), oyster and shiitake, roughly chopped); 4 shallots (finely chopped (about 1 cup)); 6 garlic cloves (finely chopped); 2 tbsp finely chopped fresh rosemary (or 2 tsp dried rosemary); 1 to 2 tbsp good-quality aged balsamic vinegar or ⅓ cup port; 2 tablespoons tamari soy sauce (or soy sauce); 1 tablespoon fresh thyme leaves (or 1 tsp dried thyme); 1 cup finely chopped toasted walnuts; 3 tbsp vegan butter; 2 small yellow onions (thinly sliced); ¾ tsp light or dark brown sugar; 1¼ tsp kosher salt or sea salt; ¾ tsp ground black pepper; 1 cup apple cider (or apple juice); 1 tbsp good-quality aged balsamic vinegar (optional); all-purpose flour (for dusting); 1 14-oz package vegan puff pastry (thawed for 40 minutes. NOTE: Not puff pastry sheets. You need to buy one large roll.); ¼ cup plain soy milk; 1 tsp maple syrup

Question

Accepted Answer

Yes, you can make the vegetable fillings up to two days in advance and assemble the vegan beef Wellington up to 1 day in advance. Refrigerate the prepared fillings separately in airtight containers before assembling. Wrap the vegetarian Wellington tightly in plastic wrap and refrigerate it before baking to serve.