Basically you can make bajjis and bondas with besan. You need a little cornflour or riceflour to get an extra crispiness. A little soda bi-carbonate(cooking soda) is also needed.This is available as a big pack in the US. See if you can get a 100gm pack in Indian stores. Or you can borrow 4 tbsp from a friend who cooks more regularly(this quantity will be good for ½ kg besan).
The besan paste for dipping bajjis and bondas is same, except that for bondas you make it a bit more thicker than bajjis.
Bajjis can be made with any vegetable, like, chillies, red pumpkin, vazhakkai (plantain), karela (bitter gourd), brinjal, Bangalore kathrikkai, potatoes, onions(slice onions in rounds) and capsicum (green peppers).
For 4 - 8 bajjis:
Besan : 3 tbsp.
Rice flour or cornflour : 2 tsp.
Soda bi carb a pinch
Salt to taste
Chilli powder 1 tsp(do not add chilli powder if you are making chilli bajjis :))
Mix all the dry ingredients well. Make a paste by adding water little at a time and stirring the mixture constantly. You will get a smooth paste. For bajjis it can be a little thicker than dosa batter. For bondas you make it as thick as idli batter. Slice the vegetables into thin rounds or long pieces, dip them in the paste and deep fry in very hot oil.