I have added only cilantro (coriander leaves). You can even add 1/4 cup of fresh mint leaves while grinding. If you are not making for fasting, vrat, or upvas, you can even add onion and garlic. Traditionally, crushed peanuts are added to the recipe. You can even add that. To make it South Indian style, you can even garnish it with freshly grated coconut at the end. If you are looking for a healthier version of sabudana khichdi, then feel free to add veggies of your choice and make a pulao instead.