with one arm tied behind one's back

with one arm tied behind one's back

Also, with one hand; with one's eyes closed. Very easily, as in I can assemble that chair with one arm tied behind my back, or I could make a better dinner with one hand, or He can do that puzzle with his eyes closed. All these phrases are hyperbolic. Also see do blindfolded.
See also: arm, back, behind, one, tie