The boat noodles at Zen Yai put me in a trance. I lose all awareness of my surroundings when I'm eating them. The people around me, the Top 40 music on the radio, the shenanigans on the Tenderloin sidewalk outside all vanish; the world is whittled down to my chopsticks, metal spoon, and the bowl of fiery red broth studded with noodles, meat, and greens. The beefy broth has the kind of heat that builds with every bite, tangy and musky, a bit sweet, and thick and rich. Soft, wide noodles provide textural counterpoints to the al dente greens and crispy pork cracklings. Bits of meat (beef or pork; I prefer beef) and liver lend their essence.
Each of the small bowls contains six or seven sublime bites, and after I've snagged the last bit of noodle and drunk the last drop of broth, I'm a little surprised to find myself in a public restaurant. All I want is another hit. And at $2.50 apiece, why not?
Boat noodles are named for the vendors who sell them from boats in waterways all over Thailand, and the reason they're so good is because the broth is made with blood. If you're not prone to culinary experimentation, please do not let this deter you. The broth doesn't have that flinty, metallic component that so many dishes made with blood can — it just adds an extra dusky layer of complexity to the broth, like pho on steroids.
The boat noodles are part of the "secret" menu at Zen Yai, though it is a secret only because it is written in Thai on the wall of the restaurant and not available on GrubHub; they're mentioned in nearly every Yelp review, and ordering them makes you about as au courant as ordering animal-style fries at In 'n' Out. Boat noodles are the reason I went to Zen Yai in the first place, but they're not the only reason to return. The restaurant has several dishes that give new dimensions to Thai cuisine for those used to pad Thai and green curry. It even gives S.F. darling Lers Ros a run for its money.
Barbecue is a house specialty, and a whole section of the menu is devoted to succulent grilled meats. The pork sausage looks like a mild bratwurst until you bite into it and your mouth is flooded with those sour-spicy notes that are the hallmark of Thai cooking. Grilled chickens, available half or whole, have a smoky, charcoal taste with a slight sweetness from a marinade. But if you're going with poultry, go with the "wing of lover" on the appetizer menu. These deep-fried wings are coated with a sticky, syrupy sauce that has infused the meat and bones with a rosy glow, and a heat that hits you in the back of the throat. They deserve to be on the short list of the best chicken wings in the city.
If I only ordered one other thing besides the boat noodles, however, I'd go with the intensely pleasurable duck curry. It had big, meaty pieces of duck swimming in a coral-hued sauce with bits of pineapple and red pepper. The duck infuses the sauce with its almost candied sweetness; this curry is creamy and rich and drinkable on its own, like a warm, savory milkshake.
Some dishes, like tom yum soup, are simply solid renditions of Thai standards you've likely had before. The tom yum's clear broth is dark with chile oil, ginger-scented, head-clearing, and full of mushrooms, shrimp, and chicken. Mango and sticky rice is a simple, favorite dessert, done very well here; the mango was almost obscenely ripe, the rice with a faint coconut flavor, and a reminder that dessert doesn't need to be fancy to be an ideal ending for a decadent meal.
There were a few disappointments. Pad Thai hit only one flavor note, and lacked the citrusy, fish-sauce-infused depth that you can find in the best versions. Spicy calamari is left over from the restaurant's former iteration as Racha Thai, and though the squid was soft and pliant in a zesty pepper sauce, the dish overall was still very fishy, almost off-putting.
Zen Yai isn't a dive. The room's deep red walls and a carved wooden column in the middle serve as atmosphere. Many of the tables around me were conversing in Thai. It was never packed like Lers Ros often is, though I've heard it can be on weekend nights, when the restaurant serves rice porridge with pork to soak up the indulgences of the evening.
But nothing else really matters when you're riding the afterglow of the boat noodles. I mentioned them to a friend, and he smiled happily, lost in a reverie of his own. We agreed to go back and eat them as soon as our schedules allow. I can't imagine we'll talk much, but sometimes contented slurping speaks louder than words.