Press the saute mode on your instant pot and heat a tablespoon of oil. Once the oil gets hot add the sliced onion and pan fry until light brown. Remove half the onions which will be used later for garnish.
In the instant pot, move the fried onion to one side and add ghee and the whole spices. Cook for 30 seconds.
Add the slit green chilly and chopped ginger and garlic. Saute for another 30 seconds.
Now add the potato (if using), tomato, salt, garam masala, coriander powder, red chili powder, mint, coriander and yogurt.
Cancel the saute mode and mix all the ingredients for 1-2 minutes. The heat in the pot will warm up the spices. Turning off the heat will helps the yogurt from not curdling. Mix it well to remove any thing stuck in the bottom of the pan. Its very important to do this step to avoid BURNT sign while cooking.
Add the boiled eggs and give a gentle mix.Add the rice and the water and mix it making sure the rice is immersed in the water. add the saffron milk, if using.
Close the lid and adjust the vent to the sealing position. Pressure cook on high for five minutes. After the instant pot beeps, wait for 5 minutes and release rest of the pressure. Add the rest of the pan fried onion and coriander leaves.
After few minutes. gently fluff the rice and serve the egg biryani with cucumber raita.