Cut the bell peppers into bite-size cubes and remove all the seeds.
Heat the oil in a saucepan. Test the heat by adding one cumin seed to the oil. If the cumin seed cracks right away, the oil is ready. Add the cumin seeds. After the cumin seeds crack, add peanuts, besan, and 1 teaspoon of sesame seeds. Stir for about half a minute until the besan (gram flour) is golden-brown.
Reduce the heat to medium-low, add the bell peppers and stir. Add coriander powder, red chili powder, and salt, then stir. Add about ¼ cup of water and cover the pan. Cook over low-medium heat for 6 to 8 minutes. Open and stir to check if the bell peppers are tender but still have some crispness to it.
Add the mango powder and brown sugar. Stir and taste to adjust salt and lemon juice according to your taste.
Turn the heat to low and cook for about 2 minutes, stirring gently.
Before serving, garnish with the saved sesame seeds. Enjoy