In small saute pan, saute mushrooms and onions in half of the butter for 5 mins. Combine the stocks in a 3 litre pot on medium heat. Add cooked mushrooms and onion. Melt remaining butter in saucepan and add crushed sesame seeds. Gradually add quarter cup of stock to the sesame seeds while stirring continuously. Add sesame mixture to the warming stock. Add salt. Cook over low heat for 10 mins. Cool broth prior to adding cream so as not to curdle cream or (*see my note above to "hurry" the process). After adding cream, stir until well blended. Heat throughly but DO NOT BOIL as separation will occur. Serve in cups and garnish with chives.