You don't really have to be precise with any of the ingredients. I have used about 1 cup of very finely chopped onions but you can decrease or increase it according to your taste. Just make sure to chop them finely.
In a large skillet, add the sesame oil or use any oil you prefer. Sesame oil is common in South Indian cooking. When the oil is hot, add the mustard seeds. When it starts popping, add the asafoetida and chilli
followed by channa dal and urad dal.
When the lentils slowly start changing color, add the methi. I add it last to avoid it from burning and tasting very bitter.
Add the chopped onions next along with salt. Saute for 2-3 minutes until its soft.
While that's cooking, chop tomatoes into small pieces. Again, the amount of tomatoes is up to you and does not need to be that precise. I think I used about 2 cups worth of chopped tomatoes.
Add it to the pan and increase the heat.
Add turmeric, stir and then cook in high heat until soft and mushy.
Add about 1 cup water , drop in the curry leaves
and the sambar powder (see Tip 3). Stir to combine.
reduce the heat to medium and cook for another 5-7 minutes with a lid closed.
I do this for the flavors to combine and the whole thing to come together as a gravy. You can at this point do a taste test and season accordingly. If you find that your tomatoes have made a sour gravy, add some jaggery /sugar to counterbalance it. Also the gravy should taste a bit salty (just a bit) since you will be adding rice to this mixture. So add more salt if needed.
Add the cooked rice. Add it cup by cup to make sure there is enough gravy to cover the rice.
The resultant rice should not be like a gravy not should be very dry.
Close with a lid and cook for another 5 minutes in low heat, for the flavors to combine well.
Switch off the flame and add 1 tsp of ghee. It improves this dish considerably and I personally recommend its addition. But if you are Vegan, you can skip it. Combine once again