When oil heats up add the mustard seeds and let them splutter.
When the spluttering stops add the onions, green chillies, ginger pieces and curry leaves and saute till transparent.
Add your vegetables now.
Add salt and 2 cups of water and wait till the water starts boiling. For every cup of semolina 2 cups of water is required.
When the water is boiling add your semolina in a steady stream while continuously stirring (utmost care has to be taken at this point or else the umpa will be full of uncooked semolina in the form of balls).
Reduce the flame once all of the semolina i's incorporated and cover with a lid for a minute and then switch off the flame and do not remove the lid for another 5 minutes.