To prepare sambar, in a pressure cooker, cook arhar dal with halved tomato, with enough water, to about 3 whistles or till mushy. Allow the pressure to release by itself. Once done, take out all the contents in a mixer grinder, grind coarsely. You can even mash it well with a wooden masher instead.
Transfer it back into the pressure cooker, add turmeric powder, red chilli powder, coriander powder, sambar powder and required salt and mix it well with a ladle.
Add the cooked and chopped bottle gourd and drumsticks and cook for 10- 15 minutes on medium heat or till it is combined well in the sambar.
In a tadka pan, heat a teaspoon of oil. Once hot, add the ingredients to temper the sambar and wait until they splutter well and switch off heat. Pour this on the sambar.
Sambar is ready! Serve hot with idli, vada or dosa!