Heat oven 220C/200C fan/gas 7. Heat the oil in a pan and cook the onion for 5 mins until soft, then set aside to cool. In a food processor, pulse the flour and butter together until the mixture looks like crumbs, then add the sage, cooled onion and enough milk to make a soft but not sticky dough. Tip out onto a floured surface, knead briefly, then roll out to 1cm thickness. Using a 1.5cm cutter, stamp out mini scones. Brush tops with egg, put onto a baking sheet and bake for 8-10 mins until risen and golden.