Sift the chickpea flour into a medium bowl. Mix in the coriander, salt, turmeric, chili powder, garam masala and garlic.
Make a well in the center of the flower. Gradually pour the water into the well and mix to form a thick, smooth batter.
Over medium high heat in a large, heavy saucepan, heat the oil to 375 degrees F (190 degrees C).
Coat the cauliflower and onions in the batter and fry them in small batches until golden brown, about 4 to 5 minutes. Drain on paper towels before serving.