I just finished up making the Bunjara, and it smells amazing. I can't wait to try it in a curry tonight with the base sauce.
I've tried caramelizing red onions before (for an unrelated dish), and wasn't very successful. They have a thin "skin" between layers, and I could never get it to dissolve or cook away. For this bunjara I used x-large "sweet onions", finely chopped in the Cuisinart. I cooked them on a medium-low heat until they were a rich, almost chocolate color. It took well over an hour.
I haven't tried it in a curry yet, but I can see how it might add that sweet, rich flavor that I associate with Indian restaurants but can't get at home. I also think it could be really versatile by using different spices blends.