In a small bowl, make a paste of mustard powder by mixing it with an equal amount of water.

Heat oil in a non-stick frying pan over medium heat.

Add the mustard paste to the pan and fry for about 1 minute until fragrant.

Add the shrimp to the pan and cook for about 5 minutes, stirring occasionally.

Pour in 2 cups of lukewarm water and bring the mixture to a boil.

Add turmeric powder, salt, and green chillies to the pan.

Reduce the heat to medium-low and let the curry simmer for 25 minutes, stirring occasionally, until the shrimp is cooked through and the sauce has thickened to your desired consistency.

Once cooked, remove from heat and serve hot with steamed rice or bread.