I know a lot of places.
La Taq - get as many Brisket tacos as you can eat (diversifying by ordering a variety will result in regret... you'll wish you went all-in on brisket)
Killer Burger - the Peanut Butter Pickle Bacon Burger is divisive. Some love it, some hate it. Their Classic is a solid 9/10 too, so go even if you have conservative tastes. Fry quality is inconsistent across locations. Sellwood location had disappointing fries when I went 2 years ago. My local location (not in Portland) had excellent fries yesterday.
Sckavone's - their Chicken and waffles is lovely
Genie's - their real claim to fame is their Bloody Marys, but the food's good too, no specific favorites
Pine State - Reggie Deluxe with cheesy grits
City State - solid biscuits and gravy or benedict. They even offer the two together in a combo
Horse Brass - no specific recommendation but the vibe is good
Matador (multiple locations) - grande nachos with steak. I recommend a mexican lager to go with it (taps rotate)
Petite Provence - their menu rotates but if you can get anything with their smoked salmon, do it
Saburo's - best quality and best value of sushi you will find anywhere in Oregon, hands down. Didn't care for the "big O" roll but everything else is good. Try the Spider roll, Sabu roll and veggie tempura (I order with no mushrooms) if you are unsure