Cut and clean the greens. Add them into a pot without water. Let them boil over medium heat. Once boiled, add oil and salt. Mix until melted. Add 2-3 tbsp of flour to thicken. In a bowl, add oil, sparkling water, salt, pepper and flour. Mix until moderately thickened. Butter the baking tray, spread the base, add the feta and slowly add the filling. Finally, dust the surface with 3-4 tbsp of corn flour.
