Soak bajra over night or you can soak for 4 hours, wash well and keep aside. Soak moong dal for 10-15 mins, and meanwhile peel and dice potato, carrot, chop beans, cut cauliflower in florets (if using) and cut any other vegetable that you would like to use.
In a pressure cooker add soaked, washed bajra, moong dal, all the vegetables, green chili, salt 1/4 tsp turmeric powder and 4 cups water, we have to use water 4 times with bajra but if you are using futura cooker you can use less water like 2 or 3 cups. Pressure cook for 3-4 whistles, after 3-4 whistles keep flame to low and cook for 5 mins.
While khichdi getting cooked, peel and chop onion, green chili, coriander leaves and tomato (I pureed tomato).
In a pan or kadai heat oil add hing, cumin seeds, mustard seeds and allow to splutter. Now add onion,
Add red chili powder, remaining turmeric powder, coriander powder and mix well cook for 1 min in low flame. Now add tomato, mix well and cook until tomato gets mashed or for 1-2 mins in medium flame.
Open cooker and add prepared masala and mix well, simmer for 2-3 mins, adjust salt if required. Off flame add coriander leaves, lemon juice and mix to combine.