Ina’s Fresh Pea Soup

2 tablespoons unsalted butter 2 cups chopped leeks, white and light green parts (2 leeks) 1 cup chopped yellow onion 4 cups chicken stock, preferably homemade 5 cups freshly shelled peas or 2 (10-ounce) packages frozen peas 2/3 cup chopped fresh mint leaves, loosely packed 2 teaspoons kosher salt 1/2 teaspoon freshly ground black […]