It all starts with the memory of a chilled asparagus soup served with black salt. It was at a friend’s house and I was smitten with the combination. I immediately proceeded to buy black salt — i.e. Hawaiian lava salt — which added nicely to my slightly frivolous collection (never fewer than five or six salts in the house at any time). And the black salt became the wallflower of my pantry cupboard. Always there, rarely noticed. But every time I did, I thought of asparagus soup.
Quite a few years later, here, then, is the ideal — though entirely optional — use for black salt.
Asparagus soup recipe inspired from Simon Hopkinson’s Roast Chicken and Other Stories
The soup requires only four ingredients and is very simple if the use of a food processor and then a food mill doesn’t seem like too much trouble.
4 small leeks
1 medium potato
600 g (1 1/2 lbs) green asparagus
120 g (1/2 cup) butter
Sea salt and freshly ground black pepper
Black Hawaiian lava salt to serve (optional)
Prepare the leeks by removing all the green leaves, slicing thinly, and washing thoroughly to remove any grit. Peel the potato and cut into small chunks.
Wash and trim the asparagus stalks to remove the tough ends. Reserve some asparagus tips to garnish the soup: about 8 to 10 tips if the asparagus is quite thin, or 4 to 5 tips to be each cut in half (lengthwise) if the asparagus is thicker. Roughly chop the rest of the stalks.
In a medium saucepan, melt the butter and stew the leeks over low heat until soft (about 5 to 10 minutes), taking care that the leeks don’t color.
Once the leeks have softened, add 750 ml (3 cups) water and the potato. Season with salt and pepper. Cook over medium heat for about 15 minutes until the potato pieces have cooked through.
Add the chopped asparagus stalks (not the reserved tips) to the soup at a lively simmer for another 5 minutes until the asparagus is cooked. *Take care not to overcook at this point, it will damage the delicate taste of the asparagus.*
Transfer the soup to a food processor and blend thoroughly until the soup is as smooth as possible. There will always remain strands from the asparagus, however, which is why the soup then needs to be passed through a food mill (or a fine mesh sieve, but I’ve always found that to be much too fussy).
The soup can be served hot or chilled. Before serving, quickly sautée the asparagus tips in a little olive oil in a small frying pan. *If reheating, use very low heat and take care not to let the soup boil as it will distort the flavor.*
The soup should be garnished with black salt or regular flakey sea salt and pepper, and/or a spoonful of crème fraîche.
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