This revolting-sounding process is in fact a trendy technique for flavouring spirits with almost any taste you can think of. We said 'fad' but actually fat washing is here to stay. It involves infusing flavours into fats and fats into spirits, then freezing the spirits to remove the fat.
We tasted a delicious, creamy example of this in a bacon and egg cocktail, made with bacon infused Bourbon shaken with a whole egg among other things. Bacon Bourbon is delicious in its own right, as well as in both sweet and savoury cocktails. Here's how to make it: Fry bacon until crispy, put it into a bottle of Bourbon (you may need to decant into a larger bottle to fit the bacon in), leave for a day or two, remove the large pieces of bacon, freeze the Bourbon until it is still liquid but all the remaining fat has solidified, and strain.
Bacon Bourbon & Egg Cocktail at the first Cocktails In The City, London 2014
The more usual use of fat washing is to soak whatever flavour you want in oil, from cherry pie to flowers to tobacco to cheese on toast, burgers, herbs, buttered popcorn, spices, leather, truffle oil or chocolate... then once the oil tastes of that thing, you use the oil alone to infuse in the spirit; freeze and strain. We've heard of cocktails made with foie gras fat washed Calvados, chicken washed Whisky and truflle Tequila.
As well as all the possibilities of fat washing with infused flavours, there's also the taste and residual texture (not oiliness, just a slight creamy richness) of the actual fat to experiment with, so cream, butter, olive oil, coconut oil, avocado oil, sesame oil etc can be flavours in their own right, for sweet or savoury cocktails.
Extra virgin olive oil would be lovely in a fresh, clean drink with flavours of tomato, parma ham and basil, but you could also make a drink that tastes of olive oil and orange blossom polenta cake. Either make the cake and soak it in olive oil, or infuse polenta in olive oil and then 'wash' your spirit (Grappa?) with the oil, before and adding orange flower water to your cocktail.
It's mind-boggling to think of all the options and combinations available to us through the medium of fat washing. So it's lucky we've got mixologists to take care of it for us.
Mai Tai made with almond fat washed Mezcal, smoked orgeat, yuzu, and Curaçao, at Empellon Cocina in New York
Spirit of Cadbury's Creme Egg
Melt Creme Eggs in a pan, and stir in a neutral vegetable oil; about twice the volume of oil to Eggs. Leave to cool, add to your chosen spirit (Vodka for pure Creme Egg flavour, Dark Rum, Bourbon or Cognac for complimentary flavours), and leave for a couple of days. Freeze and strain.
Your creation will be scrummy neat with ice or in cocktails – with or without cream – or tipped into a hot chocolate.