3 tablespoons unsalted butter.
1 medium onion, chopped.
4 cups vegetable broth.
6 cups shelled fresh peas (from about 6 pounds pods) or frozen peas, thawed.
1/4 cup fresh flat-leaf parsley leaves.
1/4 cup fresh mint leaves.
Kosher salt, freshly ground pepper.
1/4 cup sour cream.
Chopped fresh chives ( for serving)
Melt butter in a large heavy pot over medium heat , Add onion ad cook, stirring often until softened but not browned, about 7 minutes. Add 2 cups of broth bring to a boil. Add peas, reduce heat and simmer gently for about 5 minutes for fresh peas, about 3 minutes for frozen. Remove the pot from the heat. Add Parsley, mint leaves and the remaining 2 cups of broth. Puree the soup in a blender or with an immersion blender and thin it if the soup is too thick with a little water until all is smooth. Season with salt and pepper. Garnish with chives, a dollop of sour cream and serve.