Preheat the oven to 190 degrees Celsius fan. Set aside a 25cm by 38cm baking dish (I used the large baking dish from Le Creuset).
In a bowl, add the finely chopped mint, ricotta, crumbled feta, large eggs, course semolina, and seasonings. Mix well to combine.
Brush melted butter on the bottom of the baking dish. Place a filo sheet in the middle (the filo will hang over the edge of the tray) and brush melted butter on top. Repeat this with half of the remaining filo sheets, brushing melted butter each time.
Spread on the cheese mixture evenly and fold in the edges of the filo sheets. With the remaining filo sheets, fold them in half and repeat the process of layering and buttering.
On the top layer, pour the soda water. Then bake for a total of an hour, reducing the temperature to 170 degrees Celsius fan halfway through - or earlier if the tiropita has browned quickly.
Allow to cool for at least 20 minutes, before cutting and enjoying warm.
