- Heat butter in a large heavy-bottomed saucepan and saute two sliced cucumbers gently over low heat 3 – 4 minutes.
- Add dill, leek, and bay leaf and cook over low heat for 20 minutes until cucumbers are tender.
- Stir in flour until flour is absorbed.
- Add stock and salt and simmer gently 30 minutes more.
- Let mixture cool 30 minutes and then puree in a blender ½ at a time.
- Return to pan or place in a refrigerator container with tight cover, adding white pepper if desired.
- Chill at least one hour.
- Stir in diced cucumber.