Vegan Mushroom Wellington with Caramelized Onions and Spinach
A stunning plant-based version of the classic Wellington, featuring meaty portobello mushrooms layered with caramelized onions, wilted spinach, and fresh thyme, all wrapped in flaky vegan puff pastry. The mushrooms are seared until golden to concentrate their umami flavor, while the onions are slowly cooked until sweet and jammy. A homemade vegan egg wash gives the pastry a beautiful golden finish. Perfect as an impressive centerpiece for holiday dinners, special occasions, or when you want to showcase how elegant plant-based cooking can be. This version delivers all the visual drama and satisfying textures of traditional Wellington while being completely vegan-friendly.
Ingredients
- 4 large portobello mushrooms, stalks trimmed and cleaned
- 3 large onions, peeled and chopped
- 3 tbs olive oil
- 11 oz baby spinach
- 4 sprigs thyme, leaves picked
- 1 vegan puff pastryregular puff pastry1:1use if vegetarian acceptable
high
- 1 tbs dijon mustard
- salt and pepper, to taste
- 1 tbs aquafaba, chickpea water
- 1 tbs almond or cashew milk
- 1 tsp neutral flavoured oil
- ½ tsp maple syrup or brown rice syrup
Instructions
- 1
Heat olive oil in a large frying pan over low to medium-low heat
- 2
Add onions and reduce heat to low, season with salt and pepper
- 3
Cook onions stirring occasionally for 15 to 20 minutes until golden brown
- 4
Remove onions and return pan to heat
- 5
Add baby spinach and cook until wilted, then remove and cool
- 6
Increase heat to medium-high and add remaining olive oil
- 7
Place mushrooms top side down and cook for 5 minutes until lightly golden
- 8
Turn mushrooms and cook 5 minutes more until golden
- 9
Drain mushrooms on paper towel top side up
- 10
Transfer onions, spinach and mushrooms to refrigerator to cool completely
- 11
Preheat oven to 400°F
- 12
Place baking paper on baking tray and place puff pastry sheet on top
- 13
Spread half the caramelized onions over middle third of pastry leaving ¾" border
- 14
Top with half the baby spinach
- 15
Spread dijon mustard over mushrooms and season with salt and pepper
- 16
Place mushrooms on top of spinach
- 17
Top mushrooms with thyme and remaining spinach and onions
- 18
Roll pastry over mushroom mixture until you have a log
- 19
Press down to seal edges and roll so seam faces bottom
- 20
Whisk all vegan egg wash ingredients together in a bowl
- 21
Lightly coat with vegan egg wash
- 22
Place pastry in freezer for 10 minutes
- 23
Apply another layer of vegan egg wash and freeze for 10 minutes more
- 24
Place on baking sheet and bake for 30 to 35 minutes until golden and flaky
Tips
Cool the cooked vegetables completely before assembling to prevent the pastry from becoming soggy
Double coating with vegan egg wash and freezing between applications creates a beautifully golden, crispy crust
Let the Wellington rest for 5-10 minutes after baking before slicing to help it hold its shape
Good to Know
Refrigerate wrapped wellington up to 1 day before baking, or store baked wellington up to 3 days
Can assemble completely up to 1 day ahead and refrigerate before final baking
Slice with sharp knife and serve immediately while pastry is crispy
Common Mistakes
Don't skip cooling vegetables completely to avoid soggy pastry
Don't overfill the pastry or it will burst during baking
Apply egg wash lightly to prevent burning
Substitutions
high
FAQ
Can I make this gluten-free?
Yes, substitute gluten-free puff pastry, though the texture may be slightly different from traditional pastry.
What if my pastry breaks during rolling?
Patch small tears with pastry scraps and egg wash. For larger breaks, overlap edges and seal well with more wash.
How long will leftovers keep?
Store covered in refrigerator for up to 3 days. Reheat in 180C oven for 10-15 minutes to crisp pastry.