From the first official day of Autumn, instant-boiled mutton would be available in Zhengyanglou Restaurant. The lambs used were purchased from the area to the north of the Great Wall by an appointed person. Sheepfolds were also set up nearby Yongding Gate, where the lambs were first raised for some time and killed after they gained weight.
每年一到立秋，正阳楼就添上了涮羊肉。所用的羊，都是由专人从口外购买，在永定门附近设有羊圈，赶来的羊要先放入羊圈中喂养一段时间，等上了膘之后再宰杀。

After the lambs were killed, they were flayed and pressed according to different parts, namely, the parts were put on the ice with another piece of ice laid on it. After a whole day, the rammish smell would be gone and the mutton became easy to chop. According to the old people, it was the readiness of all condiments that mattered when people had instant-boiled mutton there.
羊宰后，先剥皮，然后按部位压肉，即将羊肉放在冰上，上面压上一块冰，一天一宿之后，羊肉内的腥膻杂味都被压出去掉，肉便好切了。在正阳楼吃涮羊肉，据老人们说，讲究的是佐料全。

Because of the quality of the thin mutton slices, readiness of all condiments and fresh soup, Zhengyanglou Restaurant was widely considered to be one of the best restaurants in Beijing in a short period of time.
肉好、片薄，作料全，汤又鲜，一时间，正阳楼饭馆成了北京城里人人公认的最好的一个饭馆。

In the early 1940s, like many other restaurants in Beijing did, Zhengyanglou Restaurant closed down. In 1986, at the call of the government to boost the development of the market and revitalize the time-honored brands in Beijing, Zhengyanglou Restaurant reopened on the eastern side of Qianmen Street, and changed its name into Zhengyangmen Restaurant.
到了40年代初，正阳楼也和北京城里的很多家饭馆一样关门歇业了。1986年，为了繁荣市场，恢复北京城里的老字号，正阳楼饭馆在前门大街东侧又恢复了营业，并改名为正阳门饭庄。

The specialty of the Zhengyanglou restaurant is Mongolian Hot Pot.
正阳楼的招牌菜是蒙古羊肉火锅。