Soak tamarind in Luke warm water for 15 minutes and extract the juice with around 3 cups of water
Add oil to the pan. When oil is hot add mustard seeds,channa dal, curry leaves and fenugreek and let them splutter. Add garlic and onion and sauté till the onion raw smell goes off they are cooked. Add tomatoes and little salt, cook till tomatoes mushy
Add sambhar powder and sauté for 30 secs
Add tamarind extract, turmeric powder, pepper powder, coriander powder and salt; allow it to boil for 10 - 15 minutes to get rid off raw smell of tamarind juice
Add jaggery and cook for another 5 - 10 minutes or till the Kuzhambu becomes thick