Vegan Lentil and Vegetable Wellington

Finely dice the onion; mince the garlic; very finely chop both mushroom varieties; peel and cube the celeriac and parsnip; pick and chop the thyme and rosemary; roughly chop the toasted walnuts.

Place the lentils in a saucepan, cover with cold water by 5 cm, and bring to a boil over high heat. Reduce to a steady simmer and cook for 20–22 minutes until completely tender but not mushy. Drain thoroughly and set aside.

Preheat the oven to 210°C, or 190°C for a fan oven, or gas mark 7. Toss the celeriac and parsnip cubes with 1 tbsp olive oil, a generous pinch of salt, and black pepper. Spread on a baking tray in a single layer and roast for 25–28 minutes until deeply golden and caramelised at the edges. Remove and cool.

Heat 1 tbsp olive oil in a large skillet over medium-high heat. Add the chopped mushrooms in a single layer — do not stir for the first 3–4 minutes until a deep brown crust forms on the base, then cook, stirring occasionally, for a further 8–10 minutes until all moisture has fully evaporated and the mixture is dry and almost paste-like. Transfer to a bowl.

Reduce the heat to medium. Add the remaining 1 tbsp olive oil to the same pan, then add the onion and cook for 7–8 minutes, stirring occasionally, until soft and translucent.

Add the garlic, tomato purée, smoked paprika, thyme, and rosemary to the onion. Cook, stirring constantly, for 2 minutes until the paste darkens slightly and smells fragrant.

Add the drained lentils and soy sauce to the pan. Stir to combine and cook over medium heat for 5–6 minutes, pressing some lentils against the pan with a spoon to create a partially textured, cohesive mass — the mixture must look completely dry. Remove from heat.

Wilt the spinach in a dry hot pan over high heat for 1–2 minutes, then transfer to a clean cloth and squeeze out every drop of moisture. Roughly chop and set aside.

Combine the lentil mixture, mushroom duxelles, roasted vegetables, wilted spinach, and toasted walnuts in a large bowl. Season generously with salt and pepper. Allow to cool completely to room temperature.

Cool the filling completely in the refrigerator for at least 30 minutes — this step is essential to prevent the pastry melting before it bakes.

Lightly flour a clean surface and unroll one pastry sheet. Spread the wholegrain mustard in a 10 cm wide strip down the centre, leaving a 4 cm border on each long side. Mound the cooled filling along the mustard strip, shaping it into a compact log.

Unroll the second pastry sheet and lay it over the filling. Press the edges of both sheets firmly together, then crimp with a fork to seal. Trim any excess pastry to a 2 cm border. Score the top decoratively with a sharp knife — do not cut all the way through.

Mix the plant milk and maple syrup together. Brush the entire surface of the Wellington generously with the glaze. Transfer on its tray to the refrigerator and chill for 15 minutes.

Bake the Wellington at 210°C (fan 190°C) for 30–35 minutes until the pastry is a deep amber gold and the base sounds hollow when tapped. Rest for 10 minutes before slicing with a serrated knife.