Heat the oven to 180C or equivalent. Grease two baking sheets.
Rub in the butter with the flour and salt. Add the water and pull together into a dough. Put in the fridge (to make it easier to roll out) while chopping the filling.
Chop the herbs and onion finely; halve and slice the tomatoes as thinly as you can. Put in a bowl, add the salt, pepper and a dash of olive oil and leave to combine while you roll out the pastry.
Roll out the pastry and cut into the size you would like for your turnovers. Put a bit of filling onto one side. fold, pinch the edges together and press the edges with a fork. Make three little slits in the top with a knife.
Place on the baking sheets and brush with olive oil. Bake until a light golden colour: in a fan-assisted oven it took about 20-25 mins.
This was adapted from a vegan recipe which uses yeast pastry and nutritional yeast in the filling. I also changed the seasoning as I was out of cumin, didn’t want chilli and had some sage outside. I think this recipe would also work well with some cheese in the pastry.