In a heavy-bottomed, non-aluminum pan, cook the leek, onion, and shallots in the unsalted butter over low heat until they are translucent and relaxed.

Add nectarines, six of the shiso leaves, and the chicken stock and raise the heat to a boil.

Cover, lower the heat, and simmer until the nectarines are soft.

Remove from heat and purée in a blender until completely smooth.

Pour into a saucepan and salt to taste. The salt brings out the savory flavor from the stock and rounds out the flavor.

Chop the remaining two shiso leaves. Serve in bowls garnished with a teaspoon of crème fraiche each and a sprinkling of the chopped shiso. (Alternative garnishes include chive flowers or rose petals.)