The consistency of the vada mixture needs to be just right- if the mixture is too watery, your vadas won’t be shaped properly, and they’ll end up absorbing a lot of oil while they are being fried.  If your vada mixture has turned out runny, you can add a spoonful of chickpea or rice flour into it and give it a good mix. Check the texture once again and add more of the flour if needed. It is also a good idea to adjust the amount of salt and seasonings you have added in, to compensate for the addition of the flour.