Heat ½ a tablespoon of oil in a pan and add peanuts. Cook for a few minutes i.e. until the peanuts turn crunchy. Transfer to a bowl.
Heat the remaining 1 tablespoon of oil in the same pan. Add broken red chilies, mustard seeds, urad dal, and chana dal. Saute for a few minutes i.e. until the lentils become fragrant and change color.
Add curry leaves, ginger, and green chilies, Saute for a few seconds.
Add asafoetida and turmeric powder. Saute for another few seconds.
Add salt and 2-3 tablespoons of water and cook until the water evaporates. Turn off the heat.
Add cooked rice and lemon juice. Toss until everything gets mixed well.
Finally, add peanuts and mix.
Notes
Leftover rice is the best for making lemon rice. If you don't have leftover rice, cook it at least 2 hours beforehand. Freshly cooked rice breaks easily when tossed.
You can adjust the amount of lemon juice as per your taste.
For an authentic South Indian taste of lemon rice, dry roast fenugreek seeds (methi dana) until it becomes fragrant. Allow the seeds to reach room temperature then make a fine powder. Add a small amount of this powder while adding rice and lemon juice. It won't taste bitter but will enhance the flavor of lemon rice.
Don't overcook ginger otherwise, it will turn bitter.
Adding green chilies is optional, skip if you don't want to add heat to this dish.