Caramelised Red Onion and Portobello Mushroom Wellington

Sun, 21 December 2025

Ingredients - Caramelised Red Onions

• 2 tbsp olive oil

• 2 red onions, thinly sliced

• 2 tbsp brown sugar

• 4 tbsp balsamic vinegar

• ¼ cup water

• 1 tbsp thyme leaves, finely chopped

• Salt and pepper, to taste

 

Method – Caramelised Onions

1. Heat olive oil in a large frying pan over medium heat.

2. Add the onions and cook until very soft and starting to caramelise (about 10 minutes).

3. Add brown sugar, balsamic vinegar, and water. Reduce heat and cook until thick and jam-like (about 15 minutes).

4. Stir in thyme, season with salt and pepper, then transfer to the refrigerator to cool completely.

 

The Wellington - Ingredients

• 4 large portobello mushrooms, stalks trimmed and cleaned

• 3 tbsp olive oil

• 300 g (10½ oz) baby spinach

• Leaves from 4 sprigs thyme

• 1 sheet puff pastry

• 1 tbsp Dijon mustard

• Salt and pepper, to taste

 

Method

1. Heat a large pan over medium-high heat. Add olive oil and place the mushrooms top-side down.

2. Cook for about 5 minutes until lightly golden, then turn and cook for a further 5 minutes.

3. Remove mushrooms and drain on paper towel, top-side up, allowing excess moisture to release as they cool.

4. In the same pan, add baby spinach and cook until just wilted. Remove and allow to cool.

5. Transfer mushrooms, spinach, and caramelised onions to the refrigerator and cool completely.

 

Assembly

1. Preheat oven to 200°C (390°F). Line a baking tray with baking paper.

2. Place the puff pastry on the tray.

3. Spread half of the caramelised onions over the centre third of the pastry, leaving a 2 cm (¾ inch) border.

4. Top with half of the spinach.

5. Spread Dijon mustard over the mushrooms and season generously with salt and pepper.

6. Arrange mushrooms over the spinach, sprinkle with thyme, then top with remaining spinach and onions.

7. Carefully roll the pastry over the filling to form a log, sealing the edges well. Turn seam-side down.

 

Glazing & Baking

1. Lightly brush the Wellington with vegan egg wash (see note below).

2. Freeze for 10 minutes, then apply a second light coat and freeze again for another 10 minutes if desired — this helps achieve a glossy, golden finish.

3. Bake for 30–35 minutes, or until golden, puffed, and flaky.

To Serve

Slice and serve with:

• Roasted rosemary potatoes

• Seasonal roasted vegetables