For the cream of leek soup, fry the onion in the butter until yellow. Add the leek strips and the potato cubes and salt. Add the chicken soup, cook for about 35 minutes, let it cool down a bit and puree it.
Reheat with milk and the whipping cream, strain through a sieve, season with pepper and Tabasco. Serve the cream of leek soup cooled with 1/8 whipped cream and chives.