Recipe: Iron-fortified greens soup

Green leafy veg such as watercress and spinach are good sources of iron, with 100g/4oz of watercress containing about 16 per cent of the recommended daily allowance. Even better they’re also a good source of vitamin C which is needed to help the absorption of what is called non-haem iron – the kind that comes from plants and not animals.

In fact, watercress – which is high in phytonutrients, vitamins and minerals, is such a nutritional powerhouse that the American Centers for Disease Control and Prevention lists it as number one in its list of powerhouse fruit and vegetables – the foods most strongly associated with reduced chronic disease risk.

Here Jason has taken those qualities and harnessed them into a super low-calorie, delicious soup that’s perfect for a light lunch. Its vibrant colour comes from the plant’s chlorophyl content, so if you want to make as a batch and store, be sure to follow the ice cooling technique at the end to rapidly stop it cooking before storage. Likewise, when re-heating, try to do this quickly – and take off the heat before it begins to boil.

If you have no watercress, spinach and spring greens work as substitutes. Be sure to take out the harder stalks first.

1. Bring the clear vegetable stock to boil (use a stock cube if you do not have our stock)
2. Very thinly slice the potato into water
3. Very thinly slice the leeks, shallots and garlic
4. In a separate deep solid-bottom pan, heat the olive oil
5. Add the potato and cook gently to soften but not colour
6. Add the shallots, leeks and garlic, gently cooking until soft
7. Add the green leaves and the salt, pop a lid on for a minute or two, then turn constantly
8. Cook for 1-2 minutes until most of the volume has gone from the greens, then add the hot stock
9. Add wakame (if using) and the white pepper, return to the boil. Take off when the potato is soft
10. Blitz in a liquidiser and pass through a fine sieve
11. Serve immediately, or chill over an ice bath to store (this retains the chlorophyll and keeps the soup looking vibrant)