Egg Yolk Purée

• 4 free-range egg yolks
• 5 ml (⅙ fl oz) white balsamic vinegar

Place the egg yolks in a small vacuum pouch and vacuum-pack on 100 per cent for 30 seconds in a chamber vacuum sealer*. Place the bag in a circulating water bath (or saucepan filled with water) heated to 65°C (149°F) and leave for 2 hours.

Using a hand-held stick blender, blend the yolks with the vinegar, lemon juice, oil and salt until smooth. Pass through a fine sieve and cover with a