Mix flour, water and half the salt. Knead for 5 minutes, adding water by the teaspoon if the dough is crumbly. Divide into eight balls. Cover and rest for 25 minutes.

Meanwhile soften the onion in oil over medium heat for 4 minutes. Add spinach, herbs and remaining salt. Stir just until wilted. Cook off any pooled liquid, spread on a plate and let cool.

Roll each ball into a thin 8-inch circle. Spread one-eighth of the cooled filling over one half, leaving a half-inch rim. Fold over, press out air and pinch the curved edge firmly closed.

Cook on a dry hot griddle over medium-high heat, about 1–2 minutes per side. Turn when brown spots appear and check that the sealed edge is cooked through. Brush lightly with melted butter as each comes off the heat. Serve with plain yogurt.