First make tamarind water by putting a small piece of tamarind in 1/2 cup water and mix well using hands and keep aside.  

Cook the sambar dal for 5 mts in a cooker and keep it aside. Then cook the diced vegetables with salt , tamarind water, 4 cup water for 1 mt. Mix the cooked dal and vegetables together with water as desired. Then add coriander powder, chilly powder, turmeric powder, Asafotide powder and fenugreek powder and heat it.  

Heat oil in a pan.Poppy the mustard seeds add curry leaves then add cooked dal and vegetables.Serve it hot after adding Coriander leaves.