Liqueur Caviar and Cocktail Foams

Spherification wraps a liquid in a thin gel skin, so small pearls burst in the mouth. It is striking but not for beginners.

Mix the calcium chloride into the water and refrigerate for 24 hours. Blend the sodium alginate with the water at high speed for three minutes, then add the Cointreau and keep blending; edible gold dust can go in now. Rest the mix in the fridge for at least three hours until the bubbles disappear. Drip it slowly from a syringe or squeeze bottle into the calcium bath, from neither too close nor too far. Let the pearls set for one minute, then lift them out with a caviar spoon or julep strainer. Store in a Cointreau-and-water mix for up to five days.

For a more fluid pearl that bursts more easily, reverse the roles: mix calcium lactate (2%) into the drink and use sodium alginate (0.5%) as the bath. Done in small frozen moulds, it is called frozen reverse spherification.

When a liquid mixes with another liquid it is an emulsion; a solid in a liquid is a suspension; a gas in a liquid is a foam. Shaking egg white into a sour is the simplest bar foam. Two modern styles are used:

Pour all ingredients into a cream siphon, shake hard, charge with two N₂O cartridges and rest cold for five minutes. It tops a citrus-and-vanilla vodka sour beautifully.