Lanzhou beef noodle soup with large, flat hand-pulled noodles at Ox 9 in San Mateo.

Springy al dente noodles pulled by hand and served with a nourishing beef broth are the specialty at Ox 9, a new Lanzhou noodle shop in San Mateo.

The restaurant quietly opened last weekend at 11 S. B St., at the edge of downtown San Mateo near the Caltrain station.

Ox 9 appears to be the first restaurant on the Peninsula and one of only a handful in the Bay Area dedicated to this style of fresh, hand-pulled noodles from northwestern China. The same owners operate the Lanzhou Hand Pulled Noodles restaurants further south, in Milpitas and Cupertino.

At Ox 9, the noodle-making process is on display like a mesmerizing theatrical act. From behind a glass window, customers can watch employees roll dough into chubby cylinders and then deftly stretch the noodles into existence. They drop the noodles into boiling water to cook for no longer than 30 seconds. Staff need to spend at least a decade learning to make the noodles, said owner Nina Qu, to become intimately familiar with the proper proportions, temperature and ingredients.

Customers can customize noodle dishes from six shapes and widths: from smaller round noodles similar to ramen to thick, pappardelle-esque flat noodles.

In the most classic preparation, the slightly yellow noodles arrive in a clear broth with paper-thin slices of beef, a bright red chile oil, green herbs and translucent daikon slices. The various components’ colors — clear, white, red, green and yellow — are essential standard-bearers of a traditional Lanzhou noodle soup. The broth, aromatic and flavorful, is built over 20 hours from nearly 30 ingredients.

At Ox 9, the soup ($14.48) comes with a side plate of steamed bok choy and carrots, plus vessels of soy sauce, vinegar and chile oil on the tables, for customized garnishing.

Other soup iterations come with lamb ($15.48) or pork ribs ($14.98) instead of beef. Or, the fresh noodles shine solo in brothless dishes, dressed simply in chile oil or with spicy ground pork (both ($13.48).

While the noodle soups are the main event, there are also plenty of small plates like spicy wontons, garlicky cucumbers and fried popcorn chicken.

The owners have long wanted to open in San Mateo. It’s a food-centric city with “a lot of noodle lovers,” Qu said, including a sizable Asian population. While this noodle genre is famous in China, they hope to expose more American diners to the style. The dining room is minimalist and modern, the walls decorated with enormous illustrated posters explaining the history of the “legendary” noodles and how they’re made. Diners order on their phones using a QR code, but attentive servers bring water and answer questions about noodle shapes.

Founder David Liu learned the art of hand-pulled noodles in Lanzhou before opening a shop there in 2012. He wanted to bring the specialty to Northern California and opened the first Lanzhou Hand Pulled Noodles (then called Zhongua) in Milpitas in 2017. They say it was the first dedicated restaurant of its kind in Northern California. When they expanded to Cupertino in 2021, the kitchen was overwhelmed by long lines of eager noodle fans, Qu said.

Some other Bay Area Chinese restaurants serve Lanzhou-style noodles, but it’s usually not their singular specialty. Another Lanzhou hand-pulled noodle restaurant, One Piece Lamian, opened in Fremont late last year; the East Bay city was also once home to the popular but now closed Shinry Lamian. Meanwhile, William Do of hit pop-up Laowai Noodles sells his spin on hand-pulled Sichuan noodles, but they’re hard to get with a long wait list.

Ox 9. 11 a.m.-3 p.m. and 5-9 p.m. Wednesday-Monday. 11 S. B St., San Mateo. Indoor dining and takeout. 39miles.com/z/09688759

Elena Kadvany is a San Francisco Chronicle staff writer. Email: elena.kadvany@sfchronicle.com Twitter: @ekadvany

Elena Kadvany joined The San Francisco Chronicle as a food reporter in 2021. Previously, she was a staff writer at the Palo Alto Weekly and its sister publications, where she covered restaurants and education and also founded the Peninsula Foodist restaurant column and newsletter.