This is a gorgeous, vibrant green soup. The peas add a subtle sweetness and the watercress a fresh peppery, mustardy taste. Watercress is my favourite leaf and I try to eat it every day. It’s a superfood packed with nutrients such as vitamins A, C and K and is a good source of iron and antioxidants. The little grilled cheese croutons sprinkled on top of this soup add the perfect finishing touch. This dish is ideal as a dinner-party first course – you can make the soup the day before and keep it in the fridge, then all you have to do is prepare the croutons just before you serve the soup. It’s great for lunch, too.

Heat the oil in a large saucepan over a medium heat and sauté the onions, garlic and potato for 4 minutes. Stir in the mixed herbs and vegetable stock, bring to the boil, then turn down the heat and simmer gently for 10 minutes. Add the peas to the pan, bring back up to a gentle simmer and cook for a further 10 minutes, then turn off the heat.

Stir in the watercress, then whizz with a stick blender to create a vibrant green, smooth soup. (Or you can leave to cool slightly and then pour all the ingredients into a blender or food processor before blending.) Add a pinch of sea salt and black pepper to taste.

To make the croutons, heat a medium frying pan and lightly butter each side of the bread. Fry on each side until golden and crisp. Using a sharp knife, cut into small cubes to form croutons. Sprinkle a few croutons on top of each bowl of soup before serving.