This is the best vegetarian restaurant I have been to in the Netherlands. I went on a Wednesday night with three friends and we got the last table, so next time I would consider making a reservation. Prices for a main dish run from about 10 to 20 euros. English is spoken and English menus are available.
The main dishes all seemed to consist of several different things on one plate. I had a dish which included: roasted aubergine with mozzarella and a tomato-based sauce, mushroom risotto, cauliflower and broccoli, and a chickpea patty. It sounded like a lot of food but it was small portions of each item. This all came with a salad as well. The cuisine seems to focus mostly on dishes which are naturally vegetarian rather than using meat substitutes, although a couple of dishes used seitan in this way. The food is labeled as organic.
The desserts were quite good, and far more interesting than what is generally offered in Dutch restaurants. You really should consider having one!
Note: There is a cat which wanders in and out of the restaurant. (Always a good thing to know in advance if you're allergic, but there's no category for 'resident pet.')