Here's a few food carts I have visited lately:
Q BBQ - 12th and Hawthorne: Had the pulled pork sandwich. BBQ sauce delectable. Sandwich not really possible to eat with hands, but if you do (like I did) be sure you keep the handi-wipe thingy that comes with it. You will need it.
Rip City Grill - SW Moody and Abernathy: Tri-tip steak salad, with blue cheese, caramelized onions and balsamic vinaigrette on organic greens. Like a steak dinner on greens - so tender, flavorful, and pretty. Hours: 9ish - 2ish.
Po' Town Vittles - SW Moody and Abernathy: Fried chicken salad with honey dijon dressing, currents, blue cheese and organic greens. Light, and cheap - $4.50! Hours: 9ish - 2ish. And the fried chicken is not heavy - it's crispy and flavorful and lightly breaded. Made the salad.
***Update: Ate the seafood po' boy the other day and it was fabulous! So much depth with fried oysters, shrimp and the sauce was appropriately spicy.
Grilled Cheese Grill - NE 11th and Alberta: Jalapeno Popper Sandwich with cream cheese, cheddar cheese, roasted jalapeno, ham and crushed up corn chips. I was skeptical on this one, but decided to try it anyway. Like a giant jalapeno popper, smooshed onto bread. Spicy, creamy, salty, and crunchy. YUM. Also. Pay attention to the music playing when you are eating there. You might get to hear Isaac Hayes singing Salty Balls.