Preheat your oven to 220°C/425°F, and line two baking trays with parchment paper.
In a large bowl, sift together the flour, sugar, baking powder, baking soda and cumin.
Using your fingertips, rub in the butter until you get a breadcrumb-like texture.
In another bowl, beat the egg with the water and yogurt.
Add to the flour and mix well with a wooden spoon to get a soft dough.
Add the cheese, salt and pepper and mix to just combine.
Turn on to a floured work surface and knead very lightly.
Pat out to a round 2cm/¾in thick. Use a 5cm/2in cutter to stamp out rounds and place on a baking sheet. Tip: cut the dough straight down. Don’t twist your cutter to take it out or the scone won’t hold its shape.
Lightly knead together the rest of the dough and stamp out more scones to use it all up.
Brush the tops of the scones with the beaten egg. Sprinkle with a little more cumin and/or sea salt.
Bake for 12-15 minutes until well risen and golden.
Cool on a wire rack.
They are best eaten warm (optional: spread liberally with butter), but they can be stored up to 2 days in an airtight container.