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/

1.
轻而易举, 一只手被绑在背后也能做
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.
他技术娴熟,即使一只手被绑在背后也能完成这项工作。
•
For an experienced chef, making this dish is like doing it with one hand tied behind their back.
对于经验丰富的厨师来说,做这道菜就像一只手被绑在背后一样简单。