Scovillain

You'll see these on the minimap as you progress through the Handsome Jackpot missions; they appear as small diamond-boxed grenade-like icons.  They all appear on the map well in advance of you getting close to them so they are hard to miss.

When you physically get close, Mr Torgue will speak and say something rowdy as only he can...

Hit each bottle of sauce to explode it and get the achievement.

They will mostly require some jumping/acrobatics to get to - but nothing too hard.

You can revisit areas after completing the DLC if you miss any; scout on the map to spot them.