with one hand tied behind (one's) back

Easily or effortlessly; encountering no difficulty or resistance (while doing something). I'm a professional musician, so that song is hardly a challenge—I could play it with one hand tied behind my back! Are you kidding? Montgomery is a powerhouse boxer. He'd knock that kid out with both hands tied behind his back!

with one hand tied behind your back

1. If you say that you can do something with one hand tied behind your back, you mean that you can do it very easily. This is a gadget so neat and nifty you can operate it with one hand tied behind your back. Thomas could manage the team with one hand tied behind his back.

2. If you have to do something with one hand tied behind your back, you have a disadvantage which makes it difficult for you to succeed. Our officers don't have enough powers. They are being asked to police our streets with one hand tied behind their back. Note: You can also say that you have to do something with your hands tied behind your back or that someone ties your hand behind your back. We'd like to open when our customers want us to and not only when the law says we can. Basically we're competing with both our hands tied behind our back. They insist they would have won if the politicians had not tied their hands behind their backs.

with one hand tied behind your ˈback

(informal)
1 unable to use your full powers: The government has one hand tied behind its back in these negotiations.
2 very easily; with little effort: She could run the restaurant with one hand tied behind her back.