Peel the skin & remove the seeds of the Mangalore cucumber. Chop it into 1 inch sized cubes. Add little water & cook the vegetable until soft.
Meanwhile heat a tsp of oil/ghee in pan fry raw rice, ½ tsp jeera/cumin, green chillies, ginger, coriander seeds, coconut & a string of curry leaves. Grind this to paste using required water.
Add salt, grind paste to cooked vegetable & boil it.
Beat the curd for few seconds. Add water & make thin buttermilk out of it.
Add Butter milk to boiling mixture & reduce the flame to sim.
Cook for few more minutes until it just starts to boil. Switch off the flame.
Heat a tsp of oil/ghee in tadka pan, add cumin, hing & curry leaves.