Soak toor dal for 10 to 15 mins for easy cooking. I keep tamarind also in a small bowl with little water (total 2 cups water for both soaking dal, tamarind).
Pressure cook for 5 whistles in medium flame.
Once done, mash dal and extract tamarind juice. Adjust water so that the total tamarind juice is 2 cups.
Peel chow chow, slit into two, remove the seed and the white thick part around the seed.
Slice and cut into small pieces. Boil 1 cup water and cook in low flame until soft.
Meanwhile you can peel onion, cube tomato, slit chilli.
Heat a kadai with oil. Add fenugreek seeds, asafoetida, red chilli, mustard. Once mustard pops, add cumin seeds in low flame.
Immediately add curry leaves, followed by onion and slit chilli.
Fry 30 secs, add cubed tomatoes. Fry for a minute.
Transfer to the cooked chow chow. Add tamarind extract.
In goes turmeric, sambar powder, salt and mix well. Bring to boil.
Add mashed dal and add 2 more cups water.
Boil briskly in high flame for 10-15 mins or until sambar turns thick.
Switch off the flame, garnish with some curry leaves, coriander leaves.