After eating onion/garlic just like anyone else I get a persistent stubborn onion/garlic breath & mouth wash only helps till the next time you burp it up again.

How can I flush the bad smell out of the system??

Just like alcoholism, it is a 12 step process. :)

How to Get Rid of Bad Breath from Onion or Garlic: 12 steps (http://www.wikihow.com/Get-Rid-of-Bad-Breath-from-Onion-or-Garlic)

Sardines work well