Take the grated coconut in a mixer bowl. Add 1/2 tsp mustard seeds.
Grind the coconut to a fine paste. Keep this aside.
For Cooking Vellarikka or Cucumber:
In a mud pot or kadai add 250g vellarikka or cucumber. Cucumber must be peeled and cut. Clean it well and remove water from it.
Add 2 slit green chillies and required salt.
Add enough water to cook. Mix well and close with a lid. Cook in low flame for 15 minutes.
Once cooked, add the previously ground coconut mixture. Mix well and cook in low flame for few minutes.
Add 3/4 cup curd.
Mix it and heat in low flame. Switch off before it boils.
For Seasoning:
Heat a small pan and add 1 tbsp of coconut oil. Splutter mustard seeds. Add curry leaves and few broken red chillies. Switch flame off when color changes.