Traditional Yellow Pea Soup

• 10 ounces dried yellow peas, soaked overnight in cold water to cover, drained
• 1 tablespoon unsalted butter

Heat the butter in a medium pot over medium heat. Fry the bacon for 4 to 5 minutes, until crispy. Add the onion and sauté for 5 minutes, or until soft and golden. Add the peas, stock, celeriac, leek, rosemary sprig, and bay leaf and bring to a boil, then reduce the heat and simmer gently for 1 hour, until the peas are starting to dissolve. Remove the rosemary sprig and bay leaf. Stir the soup e