Watercress and Potato Soup

This recipe is from A Year In My Kitchen

Dorothy Hartley’s 'Food in England' (one of my cookery bibles).

Talking of watercress she says ‘they reckon it is a good thing to eat in the spring. They prophesy it purifies the blood’. Well, whatever. In my state of health it’s worth a try – it’s also delicious. I find that by mashing the potatoes first, you get a particularly nice texture.

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Method

Start off by melting the butter in a large saucepan, then add the onion and let it cook gently for 5 minutes (don’t let it brown) before adding 4oz (110g) of the watercress to the pan.

Give it a good stir then cover the pan and let the vegetables sweat gently for 15 minutes. While that’s happening put the chopped potato in a pan, season with salt and cover with boiling water. Cook for 10 minutes or so until tender, then drain. Now return the potato to the pan, add the teaspoon of butter and a couple of tablespoons of the milk and whisk till smooth, using an electric hand whisk.

When the vegetables have sweated pour in the stock and the rest of the milk, then add the mash, whisking it in to get it fully incorporated. Season with salt and pepper, then put the lid back on and simmer the soup gently for a further ten minutes – make sure it is gentle because the milk can spill over otherwise.

Finally transfer the soup to a liquidiser, add the rest of the watercress and whiz the whole lot till smooth (you may have to do this in two batches, in which case have a bowl to hand to take the first batch). Stir in the lemon juice, taste to check the seasoning, then re-heat gently before serving.