IngredientsSpices
Sauerampfersorrel
Rumex acetosa, a knotweed relative. The young leaves are arrow-shaped, soft and light green, and they taste sour like a green lemon.
It is one of the seven herbs in Frankfurt's Grüne Soße and it carries the acid there. The classic sorrel soup lives on it too.
Im Topfin the pot
Heat takes the colour out. Bright green turns dull olive, almost grey, within seconds.
So it goes raw and finely cut into the cold sauce, and into soup only at the end, with the heat already off.
In Mexikoin Mexico
It is called acedera and shops rarely carry it.
Growing it is the easy route: seed is on Mercado Libre. Cut the leaves young, old ones go tough.
Ersatzwhat to use
Spinach plus lime juice. The spinach gives you leaf green, the lime the acid. Together they get the direction roughly right.
Add the juice at the end and taste, or the sauce comes out sharp instead of fresh.
Vorsichtcareful
Sorrel contains oxalic acid. In recipe quantities that is no issue.
In large amounts it is not for people with kidney trouble or gout.