Take a wide mixing bowl . In that take finely chopped onion , green chilly, coriander , curry leaves , salt, red chilly powder in a wide .
Nicely squeeze it / mix it with hand, so that onion leaves out water.
Next add maida, chiroti rava ( very fine variety), rice flour and broken cashew piece to the onion mix . Add hot hot oil to it. Oil should be so hot that wen you pour bubbles should form ( hope you can see bubbles in Pic ) .
Combine everything well . You will see that the dough will become like breadcrumb type. Keep it aside for 10 mins.
After 10 mins , try combining the dough into a single mass. Moisture from onion is sufficient to bind the dough together. So extra water is not required. But if you feel the dough is too dry, sprinkle just a few drops of water. Less the water, more crispier maddur vada will be.
Divide the dough into lemon sized balls .
Take a thick plastic sheet or butter paper. Grease the sheet as well your hands with little oil. (This helps in removing maddur vada from the sheet for deep frying). Take a small lemon sized ball and flatten it using your palm to form a small circle . Don't make it too thin or too thick. Alternatively , if you have a roti maker / press , you can keep a ball between the sheets and gently press to get a medium thin disc .
Once the oil is hot,gently holding the end of the foil in one hand, gently remove the flattened discs and drop them into the hot oil in batches of 4-5 depending on the size of the kadai used to deep fry.Deep fry them on medium low flame on both sides till they turn crisp and golden brown both sides.Once done, remove from oil and transfer to a paper towel. Repeat the same for the remaining dough.
If you don't want to fry.. you can bake them too. Preheat the oven at 180 for 10 mins. And later bake the maddur vada for 15-20 till they are crisp .
Serve Hot Maddur vada with coconut chutney accompanied with Tea/ Coffee . You can also store them in air tight containers and relish whenever you want. Remains fresh for minimum 1 week.
As far as possible try not adding any water to the maddur vada dough. Add salt and squeeze onion nicely . This will make maddur vada very crispy and also the taste gets enhanced. If you make the dough gooey , maddur vada will take in lot of oil and also end result will be soft .
Mixing hot oil gives a crispier vada and also prevents sogginess.
Dont reduce the onion quantity . Onion enhances the taste.
Don't pat the maddur vada too thin. Its not the authentic version . It should be of medium thickness such that after frying its crispy yet chewy at centre.
The temperature of the oil has to be correct while frying. The oil should not be too hot or cold. If it is hot, then the outside of the vada will get fried but the inside will be under cooked. If it is not hot, then the maddur vada will absorb more oil . To check the readiness of the oil, drop a small ball of dough (say around the size of the lemon seed). If the dough ball raises above the oil in a couple of seconds, the oil is hot enough to drop in the vadas.