Heat canola oil in a large heavy bottomed skillet until hot, but not smoking. Add okra and saute until starting to brown on one side, 3-5 minutes. Stir and allow to brown on the second side, another 3-5 minutes.
Mix the corn, onion, garlic, and salt into the skillet. Saute for another 5 minutes, stirring occasionally.
Remove from heat and mix in the butter and vinegar.
Whisk together the mayo, milk, hot sauce and garlic powder until smooth.