In a large, heavy pot over medium-high heat, melt the butter. Add the shallots and cook until they are soft and fragrant. I sprinkle Kosher salt over them. Cook them for about 5 minutes. Add the broth and bring to a boil. Add the peas (set a few aside for garnish) and cook until they are tender, about 5 minutes. Stir in the chopped mint. Remove from the heat and let cool.
Working in batches, puree the soup in a blender or food processor. Return to the pot and stir in the sour cream, yogur or creme fraiche. Remove from heat stir in the lemon zest. Season with salt & pepper. I allow it to cool to room temperatur before I set it in the refrigerator to chill completely - a few hours or overnight.
When you serve the soup, drizzle about a teaspoon of Olio D'Natalia over the top to make this soup "souper" luscious!
Pair with Fritz Chardonnay - this soup & wine are "mint" to be together.