I want to know too,
I never visited China or Taiwan, so I don't know if their restaurants use the term 「是日例湯」/ 「例湯」(soup of the day) or not.
In my experience, shanghai restaurants have no soup of the day -- the only per-made and ready to serve soup is 'hot and sour soup', it is like soup of the day everyday.
And for 茶餐廳 or 西餐館，they call soup of the day 「是日餐湯」or simply 「餐湯」
I never visited China or Taiwan, so I don't know if their restaurants use the term 「是日例湯」/ 「例湯」(soup of the day) or not.
In my experience, shanghai restaurants have no soup of the day -- the only per-made and ready to serve soup is 'hot and sour soup', it is like soup of the day everyday.
And for 茶餐廳 or 西餐館，they call soup of the day 「是日餐湯」or simply 「餐湯」