Take chana dal and soak in water for 30 minutes.
Remove the skin, wash and cut the turnip and keep it ready.
Heat oil in pressure cooker and temper with mustard, urad dal and curry leaves.
Then add the finely chopped onions and saute till transparent
Then add the tomatoes and saute till mushy.
Now add chopped knol khol and give a quick stir
Then add salt, turmeric powder and sambar powder.
Now add soaked chana dal
Then add water and check the seasoning
Close the lid and pressure cook for 3 whistles.
Open the lid and if there is little water you can switch on the stove and saute for few minutes.
Serve knol khol with hot rice.