“This is a deliciously creamy white soup, packed with lots of lovely alliums (leek, onion, garlic), which get roasted with the cauli,” says Hugh Fearnley- Whittingstall.

If you have time, leave the cashews to soak for a few hours to soften – they’ll blend to a smoother finish.

“The garlic topping is a great addition and can be made ahead, but it’s by no means essential. ”

Creamy roast cauliflower and cashew soup

Ingredients(Serves 4)

100g cashew nuts1.2–1.5 litres hot vegetable stock1 large cauliflower (about 1.5kg), trimmed and cut into small florets, leaves kept2 leeks, trimmed and cut into chunks1 large onion, roughly chopped3 celery sticks, roughly chopped1 tsp cumin seeds2 tbsp oil or melted fat5 sprigs of thyme, leaves pickedSea salt and black pepper

Garlic oil topping:3 tbsp extra virgin olive oil2 garlic cloves, finely sliced2 tbsp sunflower or pumpkin seeds (or a mix)A pinch of dried chilli flakes

To finish:A small handful of chives, finely chopped, and/or parsley

Method1. Put the cashews into a bowl, pour on 1.2 litres hot stock and leave to soak for at least an hour.

2. Preheat the oven to 190°C/170°C Fan/Gas 5.

3. Put the cauliflower florets into a large roasting tray, along with their roughly chopped leaves (if they’re in good nick). Add all the other veg and the cumin seeds. Add the oil or fat, season well with salt and pepper and toss the veg to coat lightly.

4. Transfer the roasting tray to the oven and roast for 20–25 minutes until all the veg are tender and golden.

5. In the meantime, make the topping. Put the extra virgin olive oil into a small saucepan with the garlic, seeds, chilli flakes and a pinch of salt. Place over a medium heat and heat gently for just a minute or two until the garlic starts to turn pale golden. Immediately take off the heat and pour the garlicky oil into a bowl. Leave to infuse until the soup is ready.

6. Scrape the contents of the roasting tray into a jug blender, add the thyme leaves and tip in the cashew nuts, along with their soaking liquor. Blitz until smooth. Return the soup to the saucepan and reheat gently, without boiling. (Or you can blitz the soup directly in a saucepan, using a stick blender, as you reheat it.) Either way, add a dash more stock to thin the soup a little if it seems too thick.

7. Ladle the soup into warmed bowls and top each serving with a trickle of the crispy garlic oil and a sprinkle of chopped chives and/or parsley.

 How to Eat 30 Plants a Week by Hugh Fearnley-Whittingstall is published by Bloomsbury, priced £25. Photography by Lizzie Mayson. Available now.