Sieve the flour into a bowl, add the oil and salt, then rub the mixture together with your hands. Add the ajwain seeds and slowly pour in the water as you bring the dough together. Depending on the quality of flour, you might need less or more water.

Knead the pastry briefly until it forms a ball. It should be smooth and soft.

Cover the bowl with a cloth and leave to rest at room temperature for 1 hour.

Boil the diced potato in water until soft but not mushy, then drain and set aside to cool. Heat the oil in a frying pan, add the fennel and cumin seeds, then once they start sizzling add the peas and cook for a few minutes.

Stir in the grated ginger, green chilli, ground coriander, ground cumin and mango powder. Cook for 1 minute, then add the cooked potatoes to the pan, mix well and cook for 2 to 3 minutes. Add the salt and chopped coriander then continue cooking for 2 to 3 minutes on a low heat. The vegetables should be well coated with spices. Check the seasoning, then remove the pan from the heat and leave to cool.

Place a frying pan on a very low heat. Meanwhile, divide the rested pastry into seven or eight equal-sized balls. On a lightly floured work surface, roll out each ball into a circle approximately 15cm in diameter. One at a time, lay the pastry circles into the frying pan to warm through (without cooking) then cut them in half.

Brush the edges of the pastry case with water. Bring the straight edges together to make a cone shape and spoon in some of the potato and pea filling. Pinch the open edge together and then press it with a fork to seal.

Repeat until all the remaining pastry pieces are made into samosas.