You are going about it all wrong. You can close off your nose from the inside of your mouth, near the back of the roof of your mouth.
When you do this, you taste nothing. You have to breathe out of your mouth, but you can stop and take a shot of something.
Then just chew some little pieces of ginger + peppermint leaf really good, move it around on your mouth, then swallow.
THEN open your nose again, and all you'll taste is peppermint + ginger.
It takes practice...
You can practice with juice and water. Drink the juice without tasting it, rinse with water before opening your nose, then open your nose and see how much you tasted the juice.
-Eternally Romping the Astral Savannahlands-