Dee!
The reason to add oil when cooking beans is to break the surface
tension to minimize boil-over. There is never a boil over with whole
beans. Boil over only occur with split beans, specially deocrticated
beans.
I don't pre-soak. I only add some salt before cooking in pressure
cooker.
I come from pujab region so my recipe for Whole Black Matpe Tarka is
very different. Its not a Tarka in strict sense. For Black matpe the
essentaials are fresh ginger, fresh garlic, chopped onions. I just
saute whole bunch of finely chopped a onions. Add minced garlic, and
goodly amount of coarsly chopped ginger, chopped Serrano, saute this
about two minutes. Add a chopped plum tomato. Now add the pressure
cooked Urad. The only spices added are salt, cayenne pepper and amchoor
(dry sour mango powder). Let it simmer.. Near the end, stir in whipping
cream.. Serve with a gob of sour cream. There is no traditional curry
stuff such as Turmeric, Cumin, corriander, fenugreek.. Its also called
'Ma ki Dal' or 'kali dal'.