In a heavy-bottomed saucepan, heat olive oil over medium high heat. Add onion and leeks and cook until translucent, about 5 minutes.
Add vegetable stock and bay leaf. Bring mixture to a boil, reduce heat and cover. Simmer for 20-25 minutes, until vegetables are nice and tender. Remove bay leaf from pot.
Meanwhile, generously season salmon pieces with salt and pepper.
When vegetables are done, transfer about half the soup to a food processor and puree until smooth. Alternatively, use an immersion blender to puree half. Return pureed soup to pot and mix well.
Return pot to medium-low heat and add salmon pieces. Cook for about 3-5 minutes, until salmon turns a light pink and starts to break apart. Remove from heat and stir in cream. Adjust salt and pepper to taste.