1. Pressure cook the toor dal / split pigeon peas & keep aside.
2. Heat oil in a kadai. add urad dal / black gram skinned, chana dal / bengal gram, cumin seeds & mustard seeds.
3. Once the mustard seeds starts spluttering, add a pinch of hing / asafoetida powder, shallots, green chillies, curry leaves & saute it for a minute.
4. Now add 2 tsp of sambar powder, salt to taste & mix it well.
5. Next add the tomatoes, tamarind puree (dilute it with water) & mix well.
6. Then add spinach & give it a good stir.
7. Finally add the cooked toor dal, a glass of water & mix well. at this point, check for seasoning.
8. Close it with lid & let it cook for about 10 minutes.
9. South indian style spinach sambar / keerai sambar is ready. serve it with hot steaming rice.