Pho rhymes with “duh,” and this Vietnamese beef soup claims as many legends surrounding its origin as it does American menu variations.

While there is no definitive pho history, many argue convincingly that the soup’s name is a corruption of the French word for fire (feu) in “pot au feu,” the classic boiled dish introduced to the country during Vietnam’s French occupation.

Until the French arrival, Vietnamese cows were considered labor animals and typically not food, so this makes sense.

Whatever its origin, some of New England’s tastiest and – although I hate the word’s presumption – “authentic” pho can be eaten at Portland’s Thanh Thanh 2.

Situated among the most nondescript of locations in a square white building, Thanh Thanh 2 shares a concrete parking lot with a takeout pizza chain in the traffic-heavy section of outer Forest Avenue. Nothing about its industrial facade is charming or inviting, and as a result, the restaurant feels like a locals-only secret.

Open the door, though, and watch the magic happen. First impressions include homey and warm decor with a large bar full of Asian customers during each of my suppertime visits. Matching cultural clientele is, typically, a good sign. Add a consistently friendly greeting and quick service – both for takeout and dining in – and the Thanh Thanh 2 dining experience starts well.

I acknowledge that in Asian restaurants, it’s hard to mess up Cha Gio ($3.95 for two), the crispy fried egg rolls, and Goi Cuon Tom Ga ($3.95 for two), its fresh spring roll counterpart. Even when rolls are bad, they still taste OK. Likewise, it’s difficult to note a five-star egg roll, and both Thanh Thanh rolls, the fried and the fresh, tasted OK.

The crispy fried egg rolls included a mixture of ground pork, chicken, shrimp, carrots, onions, rice vermicelli and mushrooms – served with a fragrant, homemade fish sauce. The fresh spring roll contained the same rice vermicelli, sliced chicken, shrimp and shredded lettuce, and the roll itself was equal parts chewy and overflowing – alongside a thick and salty peanut sauce.

For something a little different, but still accessible to a timid palate, try the Muc Chien Don Nha Trang ($12.95).

While the menu description, “squid salted and deep fried (spicy)” might be less than appetizing, these tangy sweet-and-sour pieces of breaded and crunchy-fried calamari were easily one of my favorite parts of the menu. The chili sauce cuts through any residual fryer oil taste, and the aromatic garlic had me craving the flavor of this dish long after the last piece was eaten.

Also a favorite, Goi Ga ($7.95) is Vietnamese cuisine’s answer to cole slaw. This salad combines pulled chicken with shredded carrots, cabbage, fresh mint, roasted peanuts and onion in a salty-sweet dressing – further endorsement that Vietnamese fare is built on a foundation of balance in texture, flavor and scent.

Now the pho. Although pho has lost some of the “it food” trendiness it used to enjoy among epicurean personalities, it’s still a major draw for Thanh Thanh 2, and a pho primer might be helpful.

Because pho originated in northern Vietnam, the dish’s history gets weirdly political. In 1954, when the country was divided, northerners fleeing communism migrated south, bringing their traditionalist sensibilities with them – and these sensibilities included a purist version of pho.

“It was embellished with more of everything – meat, noodles and broth. The practice of garnishing pho with bean sprouts, cilantro, basil and lime was introduced,” says Andrea Nguyen on her Viet World Kitchen website. “Diners also started adding bean sauce/hoisin sauce directly to their bowls. This freewheeling, adulterated incarnation reflected the southern Vietnamese penchant for eating wildly complicated food, and lots of it.”

Nguyen continues, “Then, as now, northern pho purists reacted with horror, decrying the loss of authenticity. Though philosophically liberating, tinkering with the sacred broth was an affront to strict northern cooks, whose pride and reputation rested in crafting a well-balanced bowl. Even today, what many Americans identify as the requisite pho garnish plate is hard to find in Hanoi.”

The 10 varieties of pho available at Thanh Thanh 2 (plus four more if you count the special spicy soups) can be a bit intimidating.

Traditionally, slices of raw beef steak or flank are cooked by pouring the hot broth on top, but Thanh Thanh 2 offers well-done beef options too.

Choose a combination of meatball, flank, brisket, steak and tendon from the menu in either small, medium or large sizes. (While small is a lovely portion, large provides leftovers for lunch the next day.)

With broth that’s layered in flavors of star anise and cardamom, the soup tastes deliciously complex – and deceptively simple too.

The tendon, admittedly a little weird at first, adds texture and depth to the broth, and I recommend trying it.

My personal favorite is Thanh Thanh 2’s Pho Chin Nam ($6.50 to $8.50) – beef noodle soup made with a combination of well-done beef flank and the expected garnish plate of basil, bean sprouts, chili pepper and lime.

However inauthentic these sides may be, it’s fun to customize their proportion in accordance with preference.

That noted, critics can discuss the finer points of pho’s history and preparation for hours. But the principle, especially at Thanh Thanh 2, is as simple as the broth’s humble beginnings.

Order. Slurp. Enjoy. 

Shonna Milliken Humphrey is a Maine freelance writer and author of the novel “Show Me Good Land.”