Heat oil. A wok is preferable, but if you don't have it a cast iron skillet or frying pan will work just as well. Or, if you have a deep fryer, use that. Use a thermometer, if you have one, to heat the oil to 350 degrees fahrenheit. Try and keep the temperature between 350 degrees and 375 degrees at all times so the veggies cook along with the chickpea coating and the pakoras don't change color too quickly.
Chop the vegetables. Slice veggies like potatoes and zucchini thinly, using a knife or a mandolin. You want them to cook quickly in the oil. Chop the onions and cabbage into long, thin strands. You can make them as long or short as you like, I like mine gracefully long because I love how they look once they are fried.
Whisk batter ingredients together: Place all the ingredients except the vegetables in a bowl. If the chickpea flour seems lumpy, sift it into the bowl. Whisk all the ingredients to mix.
Add the water: Slowly begin to trickle in the water, a quarter cup at a time. Whisk, and then add more. Doing this will ensure you end up with a smooth, not lumpy, batter. It's very hard to get the lumps out of the batter once you've added all the water, so doing this slowly is really important.
Check the consistency of the batter. Dip a veggie in the batter--I used a potato as you can see in the picture below. The excess batter should easily drip off while leaving a nice, even coating over the potato. You don't want a very thick batter because you should be able to taste the veggie and not just the coating, but you don't want a batter so thin that it just slides off the vegetable. To make pakoras with leafy veggies, or with veggies that have a slick surface like okra and asparagus, make the batter thicker.
Fry the pakoras. To fry the pakoras, dip the sliced potatoes and zucchini into the batter, one at a time, and place in the wok. Fry until one side turns lightly golden, then flip over and cook the other side. Flip over once or twice more. You want a lovely, golden color on the pakora but you don't want them to brown. The pakoras will continue to take on a little more color after you've taken them out of the oil. To make cabbage or onion pakoras (I do this after I've finished making the potato and zucchini pakoras), place all of the chopped veggies into the remaining batter and mix. Scoop out chunks of the batter with the veggies and add them to the frying pan.
Drain out any excess oil. When fried at the right temperature your pakoras will be perfectly crispy and not greasy, because they won't absorb much oil. Place the fried pakoras in a colander or plate lined with paper towels to absorb any excess fat clinging to them.
Serve hot. Pakoras are best served hot, but wait about 5-10 minutes before serving as the juices from the veggies can be hot and might surprise the eater when they bite into the pakora. If you need to reheat them, do so in an oven preheated to 350 degrees Fahrenheit for five minutes. Don't let them brown. These pakoras remain crunchy hours after cooking, so you can just eat them at room temperature.