There are forty thousand Mexican restaurants in the Portland metro area alone; a select few serve food that is both authentic and tasty. Many do not stay open past nine pm, however. But I'm almost positive there is only one Mexican restaurant in Portland whose extraneous events are far more interesting than anything you have to talk about, effectively preventing all desire for conversation with dining partners. This place is La Casita, and it's open until four AM Thurs-Sun!
At La Casita, MTV Español blares at all hours of the day, from many televisions. MTV Español is especially dangerous because it has no commercials, and videos for Mexican pop acts are either senseless, inexplicable, and bizarre, or so cheesy you will learn the true meaning of the word "incredulous." (There are a lot of open fields, horses, barely clothed women, chest hair, waterfalls, etc.) If MTV Español is not blaring, it is because the cook's experimental jazz trio is playing in the corner, or because it's a weekend and the disco ball/techno music is going. One time, I went in there and someone was testing the restaurant's new, huge sub-woofers, with rap music turned up so loud I thought my ears would bleed. It was awesome.
La Casita's curiosities are exciting, but obviously, the real reason to go is the food. For vegetarians, there's not much selection on the menu, but what you can eat--spicy red enchiladas with a juicy lump of white goat cheese, or an enormous vegetable burrito stuffed with Spanish rice, beans, broccoli, mushrooms, cheese, and slathered in red salsa--is flavorful, fresh, and $5-8.
Carnivores have more choices, and La Casita is so authentic you can get even get beef tongue burritos or the reportedly excellent huevos con chorizo. My dining companion eats at La Casita about six times a week. Usually, he eats two green chicken tacos, which he categorizes as "the perfect small meal, with fresh cilantro and perfectly grilled chicken. The meat retains its juice enough that if it had to be eaten without salsa, I wouldn't mind. But I drown everything in their green salsa, which is so good I wish I could smear it on my dick." Okay!