I started growing it several years ago and only last year did it actually "take". Sorrel is an easy leaf to grow, it reseeds itself every year and grows throughout the growing months. In zone 5 that means I have sorrel from May and I think I picked the last batch today, Nov 4th. Sometimes you can find sorrel at farmers markets all throughout the city, and if you can't than you can buy seeds and seed some for yourself. Since I had fresh sorrel I decided to make sorrel soup, while I write this there is only a small batch left.
I started with the rosol base and after I washed the sorrel and removed the hard stems, chopped it. Adding one tablespoon of butter, saute the sorrel until it changes from bright green to a dark khaki green, You might want to add some salt and pepper at this time. Once that's done, add it to the pot of stock that you pre-made, or to chicken stock. Next add a full tablespoon of flour and two large tablespoons of sour cream and mix together. I'd say pour but this mixture is too thick so put all of the mixture into the pot. You can then use a whisk to distribute the mixture into the soup or use and immersion blender as I do and puree the soup. I like the soup a bit tarter than what it is, so I add a couple of tablespoons of vinegar or lemon juice to the soup, based on your taste. Simmer the soup for a bit till the flavors meld together, its essentially done.
You can serve this soup as is, or you can add what we typically do, a hard boiled egg and some boiled potatoes.
You can google sorrel seeds or buy them through the link from Amazon. If there are other recipes for sorrel that you like and is not a soup I'd love it if you shared.