In a saucepan, soften the shallots in the butter until slightly caramelized. Season with salt and pepper. Deglaze with the vinegar and bring to a boil. In a blender, purée the shallots mixture until smooth. With the motor running, add the egg yolk and cream. Strain. Adjust the seasoning.
Pour the mixture into the siphon. Close to seal. Screw the cartridge to release the gas into the siphon. Shake the siphon several times upside down to allow the gas to properly mix into the preparation. Refrigerate for about 2 hours or until completely chilled.
Shuck the oysters and loosen the shellfish from their shells. Place the oysters on a platter covered with crushed ice or salt.
Shake the siphon again, upside down, to disperse the gas into the preparation. Keep the siphon vertically upside-down, gently press the lever and fill the oysters. Sprinkle with chives. Season with pepper. Serve immediately.
You can make it much easier by buying oysters in bulk (already shucked) and place them in shot glasses before topping them with foam. To make it interesting, add a drop of vodka to the oysters before the shallot foam.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.