Persian-style saffron and sweet potato frittata

MAKES 1 X 24CM 500g sweet potato, unpeeled and cut into quarters

½tsp saffron

3 large eggs

2tbsp plain flour

2tsp baking powder

½tsp bicarbonate of soda 1 garlic clove, crushed bunch parsley, finely chopped bunch mint, finely chopped bunch dill, finely chopped

20g chervil (optional), finely chopped

20g tarragon (optional), finely chopped

50g walnuts, finely chopped 50g barberries, soaked, rinsed and dried on kitchen paper sunflower oil, for cooking

For the yoghurt sauce 8tbsp Greek yoghurt ½ cucumber, peeled and diced handful parsley, leaves finely chopped handful mint, leaves finely chopped handful dill, leaves finely chopped

To garnish

rose petals (optional)

Bring a pan of salted water to the boil and cook the sweet potato for 10-15 minutes until tender. Cool a little, remove the skins, then mash and set aside.

Crush the saffron and soak in 1 tablespoon of boiling water.

Crack the eggs into a bowl and sift in the flour, baking powder and bicarbonate of soda. Add the garlic, herbs, saffron, walnuts and barberries. Season with sea salt and black pepper, then stir in the mashed sweet potato.

Add a little oil in a large, heavybased frying pan over a medium heat until it sizzles, then reduce the heat and pour in all the batter. Cook for 1 minute, then loosen the kuku around the edges. Cover with a lid and cook over a low heat for 20-30 minutes until it is just set and still fluffy. Cut into wedges.

To make the sauce, mix the yoghurt with the cucumber and herbs. Season with sea salt and black pepper. Pour the kuku into a bowl and scatter the dried rose petals over the frittata, if using.