Preheat your oven to 400ºF. Wash the sweet potatoes and bake them, in their skins, until cooked and soft. Allow to cool, then peel and mash.

Grind 1 teaspoon of the coriander seeds and the chillies in a pestle and mortar. Add the cinnamon, stir into the mashed sweet potato and season well. Fold the spring onion into the potato with the egg.

Melt the butter gently in a pan. Grind the remaining coriander seeds. Brush a sheet of filo with some melted butter and sprinkle with a pinch of cinnamon and a little of the ground coriander. Cover with a second sheet, and brush and sprinkle as before. Repeat for the third sheet. With a sharp knife, cut the stacked filo into two 6 inch squares.

Working quickly to prevent the pastry from drying, repeat with the remaining filo sheets. You should now have four squares of filo. Place a generous tablespoon of the sweet potato mixture in the centre of each square and spread out slightly. Brush the edges of each square with water and fold in half, corner to corner, to make a triangle. Press down at the edges to seal. Brush both sides of each triangle with the rest of the melted butter, place on a baking tray and bake in the preheated oven until light brown – about 10 minutes. These are your briks.

Mix the red onion with the watercress and herb leaves. Mix the yogurt with the lemon juice, a glug of olive oil and the cumin. Dress the salad with the yogurt mix and serve with the hot filo briks and the lemon halves.