A Soup of Roots, Leeks, and Walnuts

Discard the toughest of the leaves from the leeks, then cut the tender white and palest green flesh into thin rounds.
Rinse thoroughly under running water to remove any trapped grit, then add them to a heavy saucepan with the butter.
Let them cook in the butter over low to medium heat for a good fifteen to twenty minutes, without letting them color, until they are soft enough to crush between your fingers.
Once they have started to soften, you can finely slice the celery and add it to the pan, then peel and chop the artichokes and stir them in too.
Cover the pot with a lid and let the vegetables sweat and soften without coloring, then pour in the stock or water and bring to a boil.
Decrease the heat so that the soup bubbles gently and partially cover it with a lid.
Cook for about twenty-five minutes, until the artichokes are very tender.
Grind the coriander seeds to a fine powder with a pestle and mortar, then add the walnuts, mashing them briefly to a pulp.
Peel the ginger and slice it thinly, then cut it into thin matchsticks.
Warm the oil in a shallow pan, add the ginger, and fry for about thirty seconds, until it is golden and crisp.
Toss in the crushed walnuts and coriander, let them sizzle briefly, then turn out onto paper towels.
Blitz the soup in a blender or put it through a food mill, stir in the chopped parsley, and check the seasoning.
The soup should be mild and almost nutty tasting.
Ladle into bowls and top with the spice mix.