Wash and drain lentils. Soak in water for at least 8 hours.
Strain lentils, reserving water. Add lentils, water, garlic, ginger, red chili and salt to blender.
Process until smooth and transfer to a bowl.
Whisk cumin seeds & baking powder into the batter. Test to see if a drop of batter floats in water.
Gently drop 1 tbsp of batter into hot oil and fry until golden.
Place fried bhallas onto a paper towel lined plate. Place in a water bath for 15-20 minutes.
Whisk yogurt with milk, water and all the remaining spices.
Squeeze out water from bhallas. Place in serving dish and top with yogurt mixture.
Top with chutneys, red onions, chaat masala, red chili and papri.
Serve cold or at room temperature.