Adapted slightly from Vicki's Vegan Kitchen (Square One (2011)). This is a super tender, but easy to work with * For cheesy potato pastry, add 30 g (1 oz) grated mature Cheddar, Parmesan or other hard cheese plus a pinch of mustard powder to the mashed potato before cooling. For a richer colour and flavour, beat 1 egg yolk into the mashed potato.