Cut salad cucumber/southekai into small pieces. Set aside.
Sauté onion, green chili & garlic in ½ tsp of oil till its golden brown.
Once the sauteed mixture comes down to room temperature grind this along with roasted channa dal, coconut, poppy seeds, coriander leaves & tamarind to smooth paste.
Transfer grind paste to kadai along with cucumber pieces.
Add salt & water, make sure sambar is in thick consistency. (Note: cucumber will release water once salt is added, so do not add too much of water)
Prepare tempering using oil, mustard & curry leave. Add this to sambar once it comes down to room temperature.