Hi Salma,
I am from Karnataka, n here's how i prepare Rasam.
Soak tamrind (1 leamon size) in water and take out the pulp. Put it in a vessel, add little jaggery (1 tblsp) and bring it to a boil or until the raw smell goes. To this add cooked toor dal (1 cup), tomato diced (1 Large). Add salt, Hing (1/2 tsp), curry leaves. When the tomato is cooked, add Rasam powder (4-6 tsps) depending how spicy u want.
Garnish with chopped corriander leaves. Season with ghee, mustard seeds, red chilli, curry leaves and hing. Hope u like it!
16 year, 8 months ago