First of all dry roast the semolina in a nonstick pan for little time then take out in a plate.
In the same pan heat oil, when oil gets hot add in small onions and cook for little time then take out in a plate, now in same oil add mustard seeds and let them crackle, now add urad dal, curry leaves and onions.
Now cook it for 1-2 minutes at medium low heat, now add green chillies, carrot and capsicum, cook the veggies for 1-2 minutes then add tomatoes and mix well.
Now add in roasted semolina and mix well with all the veggies, cook it for 1 minutes at medium flame, stir continuously.
After 1 minute add in cooked chana dal along with water as per required and mix well then add in sambar masala, salt, turmeric powder and mix all the spices well.
Now add in lemon juice, cover and cook it for 4-5 minutes stir in between, when mixture become little thick and get cooked take out in a serving plate and garnish with coriander leaves and serve hot.