The humble Chinese burger has just received an upgrade.

If you're looking for a fresh take on an old Chinese favorite, a new specialist eatery in the capital is offering up its own modern interpretation of roujiamo - the humble street-food snack which originated in Shaanxi province and is also known as China's version of the hamburger.

This new roujiamo (literally meat in a bun) spot in Sanlitun bears the name of restaurant giant Xibei, a popular chain that serves good northwestern fare such as rolled oats, cold skin noodles, and beef and lamb dishes across all of its 323 outlets in 53 cities around China.

Sporting the name of Xibei Super Roujiamo above the door, this small and stylish restaurant is unabashed in its flamboyant approach to this cheap street snack, swapping its conventional stewed pork ingredients for a choice of creative fillings, presenting them in an unusually large triangular bun, and most importantly of all - ensuring they are delicious.

This is Xibei's first restaurant in Beijing to specialize in Chinese burgers, adding to the six other outlets in Shanghai and Shenzhen. They are part of the company's much bigger plans to open 100 Chinese burger fast-food outlets this year, says Chu Xueyou, vice-president of Xibei Group.

He says their locations will center around neighborhood communities, commercial areas, subway stations and airports, since "dining scenarios are becoming more pluralistic".

Boasting a turnover of 5.7 billion yuan ($850 million) in 2018, an increase of 32 percent over 2017, the 30-year-old restaurant brand aims to put a new spin on traditional Chinese snacks and local delicacies.

The eatery features down-to-earth decor and a brisk and happy atmosphere with an open kitchen that allows a clear view of the chefs as they are busy stir-frying, baking, and packaging. People concerned about hygiene related to traditional street food need not to worry here.

Since opening at the end of last year, this small 17-seat establishment has won a crowd of followers and sells an average of 600 roujiamo a day including online orders, according to Kong Long, head chef of Xibei's roujiamo project.

"Chinese roujiamo are closely associated to Western hamburgers. Two pieces of bread, with meat in between. If burgers can prevail as fast food in the West, why not Chinese burgers?" he says. Current dishes on offer include the signature stir-fried spicy veal in a baked bun (32 yuan), grilled lamb shashlik (33 yuan), stir-fried tomato and egg (16 yuan), and stir-fried rattan pepper chicken (26 yuan).

Kong says the fillings they have developed cater to different preferences and palates, whether they be spicy, light or vegetarian. And some more refreshing fillings will be added as the weather becomes warmer, such as Chinese shredded potato salad sandwiched in a bun.

The spicy veal filling stands out with its chunks of juicy meat and a sprinkling of mild peppers, but the other flavors are equally impressive, thanks to the sublimely chewy and soft crispy buns.

The bun (mantou), or "mo" in some northwestern dialects, is made with traditional leavening techniques without the addition of yeast or baking soda, says chef Kong.

"We only use jian (sodium carbonate or soda ash) to neutralize the sourness during the leavening process. This allows the subtle fragrance of the flour to come out, which cannot be achieved with yeast or baking soda."

Kong says the cooking philosophy behind Xibei Super Roujiamo is summed up best as "freshly cooked meat and newly baked buns", and he adds that this is not usually the case at many other roujiamo vendors and stalls where the fillings tend to be pre-made or reheated, rather than being cooked on the spot using fresh ingredients.

"To stir-fry on the spot is the key," the chef says. "The essence of Chinese flavors lies in the wok, rather than an oven or anything else. So, to achieve a great wok flavor is very important."

To prepare the fillings hours ahead or to reheat them without the "breath of the wok" in the kitchen will lead to the food losing its taste and aroma, he says.

Instead of scooping the fillings into a round flatbread split open on one side, Xibei's roujiamo is triangular, and it's around two or three times the size of an ordinary round Chinese burger you normally find. What a surprise it is, then, when Xibei serves up its roujiamo, the large triangle is cut into two halves, and diners get to grab two smaller triangular burgers.

"We made it into a triangle, not just to stand out and appear attractive, but also because we found it is easier to eat with our fillings than a round one," says chef Kong.

Kong says customers have to wait around eight minutes for one serving of roujiamo cooked to order in the kitchen. And he says that the waiting time is acceptable to customers at Chinese fast food restaurants, but may not be at Western ones like McDonald's and KFC.

Soup dishes are a great accompaniment to roujiamo, such as hot and sour potato noodles (suan la fen) in chicken soup (19 yuan). The chewy, glutinous texture of the thick sweet potato noodles is a unique creation, while the chicken soup stewed with bamboo shoots and mung bean sprouts is another popular choice.

At the hands of the chefs at Xibei Super Roujiamo, these famous Shaanxi snacks have undergone something of a transformation, reshaped into delicacies that are as satisfying as they are surprising to eat.