Chop fresh coriander leaves finely and reserve the stems. Heat butter in a pan, add bay leaves, peppercorns, onion and garlic and sauté for two minutes.
Add carrots, coriander stems and five cups of water and bring to a boil. When the carrots are completely cooked, remove them from the stock and blend to a fine puree. Boil the stock till slightly reduced and strain.
Take the puree in a pan, add strained stock to reach the desired consistency. Bring it to a boil. Add white pepper powder dissolved in a little water.
Add salt and finely chopped fresh coriander. Serve piping hot.