Wash the fresh spinach, then drop it for a few minutes in a large pan. Let cool, then squeeze them very hard to remove as much water as possible. If you are using frozen spinach, thaw it completely and squeeze it out thoroughly.
Roughly chop the drained spinach.
Slice the spring onions. Chop the dill, parsley and mint.
In a bowl, mix the spinach, spring onions, fresh herbs, grated garlic if using, and lemon zest.
Crumble the feta, add the beaten eggs, pepper generously and mix. Taste before adding salt.
In a bowl, mix the olive oil with the soda or cold water.
Lightly oil a mold. Place 4 to 5 sheets of phyllo pastry, brushing them lightly between each layer.
Add the spinach and feta stuffing.
Cover with 4 to 5 phyllo leaves, still lightly brushed. Fold the edges inward.
Brush the top, then carefully pre-cut the slices with a sharp knife.
To bake in the oven, bake for 35 to 45 minutes at 180°C.
To cook in the air fryer, bake for about 20 minutes at 180°C in a suitable pan.
Let stand for 10 to 15 minutes before cutting and serving.