Stuart Morrow’s recipe, for 15 oz: place 7.5 oz of pistachios in a container and cover with boiling water. Steep for 30 minutes. Pour out the water, place the nuts in a blender, and gently crush, gradually pouring in 7.5 oz of hot water. Pour the resulting mix into a container and leave to infuse for 2 hours. Filter the orgeat through cheesecloth into a separate container, measure the volume, and add an equal amount of sugar. Pour the orgeat into a saucepan and dissolve the sugar, but don’t boil. Cool and add 0.5 oz of vodka. Pour into a bottle and store in the refrigerator.