1) In a soup pot, cook bacon until crispy, remove to kitchen paper to drain, and reserve for garnish. Add oil and flour to pot and cook for three minutes, stirring. Add leeks and cook three minutes. Add stock. Bring to the boil, reduce heat and simmer for 30 minutes.
2) Add peas and cook for five minutes. Using a hand blender, puree soup in the pot; or pour soup into a food processor or blender, process until smooth and return to pot. Stir in cream and adjust season, to taste, with salt and pepper. Ladle soup into a warm tureen.
Serve garnished with and chives.