Heat oil in a wok/ saute pan; add urad, chana, mustard seeds, cumin seeds, dry red chili. Once the seeds start to sputter and the dals turn golden, add grated ginger and green chilies. Cook for 1 minute.
Next add onions and cashews, saute until onions turn translucent, about 3~4 minutes.
Next add the mixed vegetables and cook covered until they turn tender, about 6~8 minutes.
Add 3 cups of water and bring to a boil. Add salt and mix well.
Lower the heat and slowly add the sooji, stirring the water constantly to avoid forming lumps. Cook covered for 3~4 minutes or until sooji is cooked through and all the water is absorbed.
Turn off the heat and add the lemon juice (if using), mix well and serve. Adding 1~2tsp ghee at the very end gives the upma a very nice flavor.