Frankfurter Grüne Kräutersuppe

Frankfurter Grüne Kräutersuppe is what happens when Frankfurt's cold Grüne Soße, green sauce, gets a soup pot for spring. It belongs to Hesse, to Gründonnerstag, Maundy Thursday, and Easter week, when the first soft herbs are worth more than another cellar root. I make it when the bundle of seven herbs is bright and damp from the market, not when January herbs taste of plastic. The old larder had its months, and this is not a winter trick.

Frankfurt is strict about the seven: borage, chervil, cress, parsley, salad burnet, sorrel, and chives. Elsewhere in Hesse the arguments start over egg, quark, sour cream, and how fine the herbs should be chopped; in the south a spring herb soup may go toward chervil or wild garlic, and the north has its own green pots. Im Norden anders, im Süden anders. This one stays in Frankfurt.

The rule is simple: build the body first, then the herbs last. The floury potato simmers until it collapses, because potato gives the soup its thickness without flour, then the herbs go in off the boil and are puréed at once. Boil them hard and the green goes dull, the sorrel turns harsh, and you've punished the very thing you waited all spring to eat. Erst verstehen, dann kochen.

The cream softens it, then the acid and salt wake it up at the end. Würzen, Fett, Salz zum Schluss. A chopped egg on top nods to Grüne Soße, and stale rye fried into crumbs gives the spoon something to meet. Weggeworfen wird nichts, even in a light soup.