Well i'm guessing as a vegan, you won't want whey-based protein, nor eggs. However the hemp and chia are good suggestions. There's lots of soy-based protein supplements out there, but whether so much soy is ideal? I am not sure.
Yes, it is hard to get sufficient protein when eating a calorie-restricted plant-only diet... you really have to pay attention every day, and it can be a bit of a puzzle how to get in the protein without consuming too many carbs/calories (i.e. when you rely on beans) or too many fats/calories (i.e. when you rely on nuts).
There's a handy list of high-protein non-animal foods here www.naturalnews.com/036270_vegan_protein_l
.. gotta say, I had NO idea avocados had so much protein, or kale, or broccoli....