Wash and soak the toor dal for 1/2 an hour. Then put it in a pressure cooker along with tomatoes with enough water.
Close the lid of the pressure cooker and keep the whistle on. Pressure cook the dal until done, About 4 whistles and turn off the heat.
Allow the pressure to release from the cooker naturally, then open the lid and mash the dal into a smooth mixture using a potato masher or hand blender into a smooth purée.
Place a deep pan on heat, add 1 tbsp of oil. Then, add the slit bhindi and saute them on a medium flame until they are cooked through and lose the slime that bhindi tends to have. After about 6-7 minutes they will begin to crisp up.
Transfer this bhindi onto a plate and set it aside to be used later.
In the same pan heat the remaining oil and heat it. Add mustard seeds, fenugreek seeds, asafoetida, curry leaves and red chillies and let them crackle and crisp up.
Once done add the besan next and saute lightly till the besan gets well coated with the oil, and browns evenly.
To this gradually add a cup of water while continuously whisking, making sure that there are no lumps.
Once the besan mixture has mixed well with the water, add the puréed dal to it and mix well. Allow it to simmer gently, while adding the tamarind paste, jaggery powder and mixing again.
Bring it to a boil and allow it to simmer for a couple of minutes.
In the end, add the cooked bhindi and simmer for another 5 minutes till the Sindhi kadhi reaches a silky, thick gravy consistency and all the flavors combine well.