LAST EDITED ON 02-27-11 AT 02:24 PM (EST)
I think that doubling the lentils is a fine idea. That's what the original reciped says to do, in fact. Adding chicken is also a good idea, I think, though it's not like the soup needs it. There's plenty going on already, except for protein. Serving the soup with some simple grilled or roasted chicken would be another way to go.
ETA: I wouldn't do anything too elaborate as an accompaniment as the soup is so spicy and complex. It's almost like a chili.
I will post some pictures soon. Things have been incredibly hectic around here. You may beat me to it, and that would be great.