美人照鏡 [－－－镜]

Jyutping mei5 jan4 ziu3 geng3
Pinyin měi rén zhào jìng

Definitions (粵典–words.hk)

語句
將碟上面嘅食物食到乾乾淨淨；形容到隻碟好似塊鏡噉，畀貪靚嘅美人照清楚
to have eaten all the food in one's plate; literally: the beauty looks into the mirror

Definitions (Wiktionary)

phrase, Cantonese, Hong-Kong, idiomatic
to finish one's plate; to have eaten all one's food for a meal

Jyutping mei5 jan4 ziu3 geng3
Pinyin méi3ren zhào jìng

Definitions (CC-CANTO)