More information on hing can be read here. It is one of the great flavors in Indian Food.
I love hing so I use it literally on everything I make. :)
The brand I usually use is LG. I tried Vandevi once and it I felt it is just turmeric powder, did not actually have the flavor of the real hing.
So the last time I went to India, I saw my grandmother using this block of hing and the food tasted awesome. So when i came back, I found this in the Indian Store (again LG brand Block Hing) and of course Immediately bought it home. This beats the powder by many times.
I wrapped the block in an old kitchen towel and pounded it with a hammer until it became to an 1 inch pieces and put all of them in the Indian Mixer Grinder and ground to a fine powder. When I open the bottle, the kitchen smells FANTASTIC!! It took a total of may be half on hour. It is not an easy task but well worth it.
Please do give this a try!!