Sift the plain flour, semolina, bicarbonate of soda and a little salt together into a large bowl.
Add the warm oil and enough water to make a stiff dough.
Set aside for about 30 minutes, or until risen.
For the filling, cook the potatoes in a pan of boiling water for about 20 minutes, or until soft, then drain and allow to cool.
When the potatoes are cool, peel off their skins, return to the pan and cut into dice.
Put the diced potatoes, chilli powder, chillies, chickpeas, moong beans and chopped coriander into a large bowl and mix together.
Put all the ingredients for the masala for sprinkling in a bowl and mix together, then set aside.
Divide the dough into equal portions and roll into 15-20 balls.
Flatten each ball between the palms of your hands and place a portion of the filling in the middle.
Shape again into balls then, using a rolling pin, roll into discs of about 10cm / 4 inches diameter.
Heat the oil for deep-frying in a kadhai or deep, heavy-based pan to 180'C / 350’F, or until a cube of bread browns in 30 seconds.
Working in batches, carefully lower the kachoris into the hot oil.
Deep-fry, turning frequently, for about 2-3 minutes, or until coloured evenly all over.
Remove with a slotted spoon and drain on kitchen paper (paper towels).
Allow to cool.
Pinch a hole in the top of each kachori and stuff it with the rest of the filling.
To finish, spoon the chutneys and whisked yoghurt over the top, sprinkle with the masala and serve immediately.