Beat the eggs with the yoghurt, 2-3 tbsp oil, a little salt and the carbonated water.
Divide up the phyllo pastry sheets into 2 piles. Crumble feta cheese on the pairs of sheets from 1 pile. Stack them one atop the other until out of sheets.
Wrap up loose rolls from the other pile and then cut them into 1 1/2″ (4 cm) thick rolls.
Bake in a preheated 356°F (180 °C) oven until golden.