Combine yeast and 60ml lukewarm water in a small bowl and stand in a warm place until foamy (8-10 minutes).
Combine sugar, lard and ½ tsp salt in a large bowl, add milk, cream and 125ml boiling water and stand until lukewarm. Add yeast mixture and egg, whisk to combine. Sieve over flour, mix to a dough, turn onto a lightly floured surface, knead until smooth, wrap in plastic wrap and refrigerate to rest (1 hour).
Heat oil in a deep saucepan to 180C. Divide dough in thirds, roll out each piece to 3mm thick, then cut into rough 5cm diamonds. Deep-fry in batches, turning occasionally, until golden and puffed (2-3 minutes; be careful as hot oil may spit), drain on absorbent paper. Dust generously with icing sugar and serve hot.