Saw this van on the roadside, just past Paia town enroute to Haiku. Stopped for a sandwich just this week. Here's my Da Falafel King reviews.
The side of the fan reads "Falafel" so you can easily spot it. The menu is short with option of half sandwich for $5, full sandwich for $8 (Dec 2012 prices). You could also get falafels alone or with nutella (dairy).
I got a full side sandwich, and it was tasty and filling. The tahini dressing is vegan suitable and yummy.
However, it is a lot of fried food (falafel), so I felt a need to drink a cup of green tea afterwards to wash it down. My tummy felt uneasy for a while that day, so maybe a half sandwich would have been enough.
Surprised to find that this van accepts credit card payments.