First, rinse and clean the urad dal. Soak it in water for 5 hours. After soaking, rinse it 2-3 times and drain in a strainer to remove excess water. Add just enough water to grind the dal in a blender until smooth, then transfer to a large bowl. Whisk the batter with clean hands in one direction until it becomes light and fluffy. To check, drop a small amount in water—it should float. Add asafoetida, salt, cumin powder, and black pepper, and mix well. Heat mustard oil in a deep pan over medium heat. Take a little batter in your hand, shape it into vadas, and gently drop into the hot oil. Fry on medium heat until golden on both sides.

Remove the vadas and place them in warm water with a pinch of asafoetida. Let them soak for a while until they puff up. Meanwhile, whisk the yogurt until smooth.

Add roasted cumin powder, red chili powder, powdered sugar, and black salt to the yogurt and mix well. Squeeze the soaked vadas gently to remove excess water and add them to the prepared yogurt.

Sprinkle the roasted spices on top. Serve in a bowl, drizzle with tamarind chutney, and sprinkle more roasted cumin powder, red chili powder, and black salt as desired.