Soak rice and urad dal separately in water for 5-6 hours.
Grind the soaked urad dal until it becomes light and fluffy. Do the same with the soaked rice.
Mix the ground dal and rice together and add salt according to taste.
Let the batter sit for 4-5 hours to ferment well. The level of fermentation affects the idli's softness and fluffiness.
In a pan, heat ghee and add cumin seeds. Once they splutter, add all the vegetables and the required amount of salt. Cook on medium flame for a few minutes, stirring frequently.
The vegetables don't need to be fully cooked as they will steam with the idli batter later. Remove from heat when they are half done.
Let the vegetables cool down, then mix them with the idli batter.
Spoon the batter into idli molds and steam for about 15 minutes or until a toothpick inserted in the center comes out clean.
Servethe idlis hot with chutney or Sambhar.