In Udupi cuisine, dals are not extensively used in sambars, but are used in making chutneys. Horse gram chutney, toor dal chutney to name a few(actually, I only know these two :) ).
Horse gram is claimed to make the bones strong(source - Veena :D). It is used in rasams, uslis(stir fry), chutneys, idli. You need an acquired taste to enjoy this. I didn’t like hurali(horse gram) as much when I was a kid, but nowadays I am a big fan.
Horse gram - handful - 3 tbsp
Coconut - handful - 3 tbsp
Urad dal - 1 tsp
Red Chili/byadagi menasinakayi - 3
Tamarind paste - 1/2 - 1 tsp
In a pan, add oil. Roast urad dal and red chili in medium heat, until urad dal changes color. At this point add horse gram and fry till it puffs up.
Switch off the stove and add coconut and curry leaves. Let it cool a little bit.
Grind semi-coarsely in a mixie along with tamarind and salt, adding water as needed.
Make tadka and add to the chutney.
Enjoy with some hot rice and papad.