This is a classic in our family. My mother used to make it when we were growing up. Originally she could not find Sorrel in this country, so she substituted beet greens and lemon. Eventually she grew it at home (it’s a fairly hardy perennial weed) with the help of her cousin Irmgard. It also became available at the Ithaca Farmer’s Market. Her version of the soup is a bit lighter on the sorrel than mine is, but for that reason may be a bit healthier.
For the health conscious you should know that Sorrel is chock full of oxalates. Oxalates are a key component of calcium oxalate, which is what most kidney stones are made of. One way to mitigate the effect of these oxalates is to consume a calcium rich food with the sorrel so that the calcium oxalate is formed in the gut instead of the kidneys. Hence the recommendation to add some dairy to the soup.
I believe the version published on Finger Lakes Feasting is based on my mother’s, though I suspect she used less than 1/2 a pound of sorrel per quart of liquid.
Here are my notes and hints.
I usually stem the leaves as I wash them to get a smoother soup.
The potato gives a nice, thicker texture to the soup.
I discovered that using a blender stick (we have the Hamilton Beach) is a great way to blend the soup: it is much less messy and saves ladling things back and forth.
Sour cream or yogurt are good substitutes for the half and half.