Like many other achievements so far, if you have an existing 360 save with [required item], in this case a Nether portal, you can cheap out and get the achievement easily.
You'll need your existing portal, a diamond pickaxe, and flint and steel. Use your pickaxe to take out one of the obsidian blocks bordering the purple field. When it breaks, pick it up and replace in the same spot. Use the flint & steel on the open portal "window" and the purple haze returns, your achievement pops, and you feel slightly more guilty than when you built the thing with the 'bucket trick' on the 360 originally...