I hope this might help someone, if not now - in the future. It's an interactive map of Food Carts in Portland. Forgive me if this has been discussed already on here.
There are filters for type of food, neighborhood location, hours of operation, etc. I don't know how often it is updated, or where the data comes from - but it is a service of bing.com
Here is a link to the Food Cart finder: http://tinyurl.com/pdx-foodcarts