someone could do something with one hand tied behind his/her back

US /ˈsʌm.wʌn kʊd duː ˈsʌm.θɪŋ wɪð wʌn hænd taɪd bɪˈhaɪnd hɪz hɜːr bæk/
UK /ˈsʌm.wʌn kʊd duː ˈsʌm.θɪŋ wɪð wʌn hænd taɪd bɪˈhaɪnd hɪz hɜːr bæk/
"someone could do something with one hand tied behind his/her back" picture
1.

輕而易舉, 一隻手被綁在背後也能做

to be able to do something very easily, even under difficult circumstances

:
He's so skilled, he could do this job with one hand tied behind his back.
他技術嫻熟,即使一隻手被綁在背後也能完成這項工作。
For an experienced chef, making this dish is like doing it with one hand tied behind their back.
對於經驗豐富的廚師來說,做這道菜就像一隻手被綁在背後一樣簡單。