AS I TRAVERSE the city, continuing to hunt down the perfect taco, I've been asked, "Why tacos?"

While it's true many of the taco trucks I've eaten at have so much more to offer than tacos, I feel the small foldable gems represent, in their simplicity, the perfect litmus test for any truck.

A taco does not allow the meat to be hidden. It is laid bare to be experienced in full. A burrito is too complex. It's too easy to hide poorly prepared meat in a wash of rice, beans, salsa, and guacamole. If you find good meat in a taco, that same quality will be represented in whichever menu item it appears. So it's tacos now, everything else later. Here are this month's trucks. (Note: Hours are subject to change, as the whims of the truck are unpredictable.)

Taquería la Express #1

Roaming NE Portland

Open daily from when they start until they stop

$1.50 tacos

There is a semi-secret community of taco trucks that flit like dragonflies from one workplace or job site to the next. Recently, while driving south on MLK, the smell of carnitas began wafting through my windows. I suddenly noticed I was two cars behind Taquería la Express. Giving chase, I followed the truck to N Columbia and Congress, where it stopped in front of a towing company. They seemed a bit startled when I walked up to order.

If you're lucky enough to happen upon Taquería la Express, order the asada. The meat is slightly charred from the grill but deeply tender and moist. It's very flavorful, seasoned in part with cumin, and just spicy enough. The truck features a self-serve salsa bar that includes four types of salsa, sliced radishes, and an outstanding spicy pickled carrot and jalapeño mix. Onion and cilantro standard.

El Brasero

SE 12th & Hawthorne

Open daily 6-3 am

$1.25 tacos

A proud member of Hawthorne's cluster of late-night carts, El Brasero has the gumption to close for only three hours every morning, keeping the foodie parking lot humming throughout the day. There is a full complement of Mexican specialties, but of the tacos, the pastor and chorizo are easily the best bets.

The pastor is far less saucy than what I've found at other trucks, making it very easy to eat. It lacks the serious spice of some pastor, but does have a bright and subtle sweetness that makes the meat taste light. The chorizo is another matter. The spicy pork sausage has excellent heat, with a subtle maple sweetness that is enhanced with a squeeze of lime. The added citrus makes this taco bloom with a deeply complex flavor. Onions, cilantro, and lime standard. Certainly veg and vegan friendly. (Cactus, anyone?)

Tacos y Tortas Morelia

SE 52nd & Foster

Open Tues-Sun 10 am-9 pm, Mon 10 am-6 pm

$1.25 tacos

Sometimes you come upon a truck that offers tastes so foreign to your surroundings that it's necessary to collect yourself for a moment. Such is the case with the birria taco at Morelia, made with goat meat. Goat has a funkiness that I have always enjoyed, similar to well-aged goat cheese. The slightly greasy but deeply savory goat taco prepared at Morelia retains a good deal of that goaty funk. However, the coup of the Morelia birria taco is its additional dark dollop of mole sauce.

On the second bite, there it was, rich and creamy with that cocoa-esque mole twang blending perfectly with the goat, creating a balanced and complex taco flavor that removed me from my own reality for the duration. I did manage to return. Onions, lime, and cilantro standard.

Taqueria Los Gorditos

SE 50th & Divison

Open Mon-Sat, 11 am-8 pm

$1.75 tacos

Of all of the strange things I've eaten from a taco truck (head, tongue, stomach, etc.), perhaps the strangest is tofu. But tofu and soyrizo (vegan chorizo) are what keep this Southeast gem hopping from open 'til close.

Don't get me wrong. Los Gorditos does wonders with meat as well—their Stacey burrito fueled my late-summer evenings last September during the Time-Based Arts festival.

Still, the tofu taco is not to be trifled with. Far from bland, the chunks of tofu taste like they've been marinating in a savory broth for days before being fried. The texture is excellent—reminding me of a perfectly juicy lengua taco—and the refried beans that line the tortilla work to add that extra oomph. Veg and vegan friendly (notice how difficult it is to read the meat menu). Cilantro and onion standard.