Wash and slice 2 large potatoes, 2 large onions, and 1 large eggplant into thin, round slices. Set aside.
In a large mixing bowl, combine 250 grams of besan (gram flour), 50 grams of rice flour, 1/2 teaspoon of red chili powder, 1/4 teaspoon of turmeric powder, a pinch of asafoetida, and salt to taste.
Gradually add water to the dry mixture and whisk until you achieve a smooth, thick batter consistency.
Heat oil in a deep frying pan or kadai over medium heat. To check if the oil is hot enough, drop a small amount of batter into the oil. If it sizzles and rises to the surface, the oil is ready.
Dip the vegetable slices one by one into the batter, ensuring they are fully coated.
Carefully slide the coated vegetable slices into the hot oil and deep-fry until they turn golden brown and crispy.
Use a slotted spoon to remove the bajjis from the oil and place them on a plate lined with paper towels to absorb excess oil.
Serve hot with coconut chutney or tomato ketchup.