Heat oil in a pan over medium heat. When the oil is hot enough, add mustard seeds. Wait until the mustard seeds pop up.
Now, add chopped onions and green chillies. Sauté until the onions become soft.
Add ginger garlic paste and sauté for a minute.
To this add the snake gourd pieces and turmeric powder. Sauté for a minute.
Cover with lid and cook for 2 to 3 minutes over medium heat.
Now add red chilli powder and a little salt.
Stir well until well combined, cover with lid and cook again for 2 minutes over medium heat.
Add milk and cook over medium heat till the vegetable is completely cooked and you get the desired consistency. Adjust salt if required.
Turn off the heat and garnish with finely chopped coriander.
Serve Snake Gourd Curry with rice, roti or paratha.