The legendary chef from Szechuan and Mao's deceased mother. She was the former Master Chef of Kikkaro Restaurant. Pai was called the 'Szechuan Fairy', or the 'Fairy of Cuisine', and was one of the most respected chefs in all of China. Even though she didn't directly teach Mao her cooking techniques, she did teach him her ideals. She taught him how to use cooking to make people happy and healthy.
Pai was such a great chef that she was considered a threat to the Underground Cooking Society. In her early years as a chef, the Underground would always send chefs to battle her, which she always won. She even made a notebook compiling all the information she gained from battling chefs from the Dark Cooking Society, which would include the Dark Cooking Techniques that they used against her. Mao would eventually come to have possession of this book.
In the manga, it is revealed that she died from exhaustion. After her former pupil, Shouan, became a Super Chef, he stole all the chefs that were cooking in her restaurant, making her do all the work on her own. Though she died, her teachings would live on in her son, Mao.

(Source: Wiki)