In which kind of food items can Asafoetida be used?
I have only seen it used in dahl dishes, presumably because of it's claimed digestive properties. Asafoetida is incredibly pungent; anything more than a pinch seems too much and unpleasant.

I think of it as a flavour-enhancer, a natural, Indian MSG rather than a spice in the normal sense. It makes your mouth water quite intensely and seems to stimulate the savory tatse buds (umami). This is lovely when done subtley and kept in the background.

Therefore, I suspect you could add small pinches to all kinds of savoury food.