Momo is the type of place where you might stop for lunch or breakfast or a quick bite to eat. They had two veg. options when I visited, a mediterranean style veg. sandwich and a hummus sandwich.
For some reason, the hummus also had cheese in it which was a slighty odd combo. They could probably split that into either a hummus or a cheese sandwich and have a better result. The veg. sandwich however was delicious, one of the best I've tasted anywhere.
We just got Turkish tea at the time but it looks like the coffee here could be quite good too, they have a proper barista-style machine setup and some funky coffee cup decoration.
The prices seem slightly steep for Istanbul but probably worth it. Location is a 10 minute downhill walk from Taksim square, in one of the trendier parts of the city.
Cons: Prices a bit high, Small place so limited selection