Golden Temple has fanstastic vegetarian and vegan food! It's not cheap, but worth it. They have a great website: http://www.restaurantgoldentemple.com/. Check out their vegan page. Golden Temple is located at Utrechtsestr 126.
I had the Mezze Platter. You get to choose four items. I picked a skewer with peanut sauce tofu and broccoli, a yam curry, chickpea and vegetable stew, and eggplant curry. All this comes with couscous and pitabread.
Maoz Vegetarian is a quick and cheap falafel shop. I had falafel and fried eggplant. Delicious! I went back for another one a couple of days later. For 5.50 euro, you get your sandwich and can top it from the salad bar with anything you wish. Maoz Vegetarian originated in Amsterdam, but can be found in many locations (United States, France, Spain, U.K., Austrailia). The website tells their story and has all the U.S. locations. http://www.maozusa.com/about. This shop in Amsterdam was on Damrak.
Haesje Claes is terrific for authentic Dutch food. Unfortunately, there is nothing vegan on the menu except a side salad. I asked the waitress if that was my only option since I was vegan. She checked with the kitchen crew and then said they would be happy to whip something up for me. And... it was incredible!!!
First arrived a green salad topped with walnuts, beets and a vinaigrette. Then came my fabulous vegetable entree. This picture doesn't do it justice. There are more fabulous veggies hiding underneath the white asparagus and sauteed mushrooms. The cook sauteed vegetables in olive oil and fresh herbs - cabbage, green beans, carrots, squash, etc. It was accompanied by olive oil mashed potatoes instead of the butter and cream version.
The white asparagus spears were HUGE! This dish was lot bigger that it looks. My salad was about 4 euro and the main dish was 8 euro. Haesje Claes has a website: http://www.haesjeclaes.nl/?language=en_EN and they are located at Spuistraat 273-275.