In a bowl, mix 250 grams of all-purpose flour (maida) with 1/4 teaspoon of salt and 2 tablespoons of oil. Gradually add water and knead to form a soft dough. Cover and let it rest for 20-30 minutes.
In a pan, heat 2 tablespoons of oil. Add 1 teaspoon of cumin seeds and let them crackle. Then, add 1/2 teaspoon of finely chopped ginger and 2 finely chopped green chilies. Sauté for a minute.
Add 2 cups of finely chopped onions and cook until they turn translucent. Add 1/2 teaspoon of turmeric powder, 1/2 teaspoon of red chili powder, 1/2 teaspoon of coriander powder, 1/2 teaspoon of garam masala, and salt to taste. Cook for 5-7 minutes until the spices are well-blended and the mixture is dry.
Add 2 tablespoons of chopped coriander leaves and mix well. Remove from heat and let the onion filling cool down.
Divide the dough into equal-sized balls. Roll each ball into a small circle, place a spoonful of the onion filling in the center, and seal the edges to form a stuffed ball. Flatten the ball gently with your fingers.
Heat oil in a deep frying pan. Once the oil is hot, carefully slide the kachoris into the oil and deep-fry them on medium heat until they turn golden brown and crispy.
Remove the kachoris from the oil and place them on a paper towel to drain excess oil. Serve hot with mint chutney or tamarind chutney.