A recent movie review of Forks Over Knives in the Boston Globe speculated that vegans must have a hard time with protein and essential nutrients.
Somehow the average consumer has forgotten that plants are filled with protein (i.e. have you ever heard the term "textured vegetable protein"?)
As a vegan for over 10 years, I've never had any issues with protein, necessary amino acids, or essential nutrients. I get everything I need from a simple balanced diet that includes protein rich plants such as spinach, soy, and peanuts.
Here's a useful resource about the protein content in vegetables.
How do vegans get enough protein? Just pass the spinach!
Here's a few favorite protein rich recipes.
About the only issue vegans have is getting enough B12. I need about a thimbleful per year! I can just get it from B12 found naturally in the topsoil that sticks to root vegetables (no matter how much you clean them) or take an occasional supplement extracted from yeast.
No meat, milk, or cheese required!