Heat oil in a pan and roast the Radish (daikon) until the edges change color and keep it aside.
In pressure cooker add pigeon pea, split green gram, little cumin, 2 1/2 cup of water and pressure cook for 4 whistle.
In a pan add roasted Radish (daikon), little water, salt and bring to boil. Now add sambar powder, turmeric powder and boil. Now add tamarind juice and bring to boil. Now add cooked (Pigeon pea + spit green gram). Boil and cook for 5 minutes. Remove sambar from heat and keep it aside.
In a pan heat oil. Add mustard seeds, cumin seeds, shallot (sambar onion), curry leaf and sauté until the shallot (sambar onion) turns translucent. Once onion is sautéed add asafoetida powder. Now add this to sambar. Mix well and serve.