To make your mayonnaise whisk together your egg, vinegar, mustard, paprika and half of theseasoning salt until it is foamy.
Slowly drip in the olive-canola oil mixture and whisk until it is all combined. (You should end up with a mayonnaise resembling the color of 1000 island dressing or Big Mac sauce)
Fine dice your red onions and add them and the relish to the Mac sauce mayo base and your sauce is done!
Take your ground beef out of the package, pat it dry with a paper towel and lightly shape it into 3/4lb patties.
Season each patty on both sides with a good sprinkle of seasoning salt.
Heat your (ideally) cast iron pan, flat top or frying pan to medium-high so the whole burger caramelizes and browns all around. Cook 4 minutes per side for medium doneness.
Set the meat aside to rest, add butter to the pan and toast those buns until they’re slathered in butter and golden brown!
Finely chop the lettuce right at the last-minute so it’s fresh and crisp.
Assemble the burger with the toasted bun, meat, Mac sauce and finely chopped lettuce.