I used ½ cup toor dal/tuvar dal/split pigeon peas, pressure cooked with 1 cup of water with little turmeric. Pressurecook it for 4-5 whistles. Let the pressure release on its own. Mash it wellandkeep aside until use.
Wash the tomatoes, chop it fine. Add water to a heavy bottomed vessel, i used my eeya chombu/tin vessel for making the rasam. Add chopped tomatoes to this. Keep this is on stove and let it start to boil.
I normally crush the tomatoes as both my kiddos pick out the tomatoes, if you don't mind the tomatoes in rasam, then you can chop them fine and add it to the water.
To this boiling tomato water, add green chili, rasam powder and salt. Cook it until the rawness of the rasam powder disappears
Now add the cooked dal to this rasam.Let it sit on the stove in a simmer flame for 5 -8 minutes. When it froths well, remove it from the flame.
Add the lemon juice. Do not boil the rasam after adding lemon juice. Garnish with fresh coriander leaves and grated ginger
Now for the tadka, heat a tadka pan with ghee. splutter mustard seeds, add cumin, pepper powder, red chilies, hing and curry leaf. Pour this sizzling tadka over the rasam. Keep it covered.
Serve it warm along with rice and curry. I served it as part of our Weekend Lunch Yennai Kathrikaai kuzhambu, yardlong beans paruppusli.