Since 2009 i experienced a lot of vegan/vegetarian menu on the flight, mostly taste so awful. Not many choice, the airlines will serve you kind of rice india curry with less taste.
The best vegan/vegetarian meal that i have so far is Vegan Ala Carte Menu from KLM Royal Dutch Airlines, at least from my experience after 3 route flight.
This flight is veggie friendly. For example they have almond & soy milk if you want for your coffee. Even the sandwich/bread snack for all the passanger, they use vegan menu.
Worth a try !
