In a large saucepan melt the butter. Add the onion and garlic and cook gently for about 5 minutes until the onion is soft but not brown. Add the tomatoes. Simmer gently for 10 minutes, breaking down the tomatoes with a spoon. Add the stock, bay leaf and sweetcorn kernels. Season to taste. Bring to the boil, then reduce the heat and simmer for 30 minutes. Discard the bay leaf. Pour the soup in a blender or food processor and process well until smooth; this may have to be done in batches.
Return the soup to the saucepan. Stir in the cream and heat gently to just below boil ing point; do not allow the soup to boil. Serve in a warmed tureen with chopped coriander sprinkled over