Wash and soak cowpeas for at least 6 hours. I usually soak it overnight.
In a pressure cooker add soaked cowpeas, garlic cloves, chopped tomatoes, salt, turmeric powder and 3 cups of water. Pressure cook on high flame for 5 whistles. Let the pressure release on its own.
In a kadai, heat oil and add mustard seeds. Once the mustard seeds crackle add chana dal, urad dal and asafoetida.
Immediately add chopped shallots, curry leaves and red chillies.
Once the onions turn transparent, add sambar powder, mix well, saute for just under a minute and switch off the stove.
Now open the pressure cooker once the pressure has released completely and check whether the cowpeas are thoroughly cooked. If not, cook for 3 more whistles.
Now add chopped brinjals and bottle gourd to the cowpea in the same pressure cooker.
Add the tempered onion & sambar powder mixture, tamarind, ½ cup water if needed and pressure cook again for 1 whistle in medium flame.
Allow the pressure to release naturally and garnish with coriander leaves.