Prep and heat up your grill to medium-high heat.
Combine the pesto and mayonnaise in a small bowl and mix well. Set aside.
Divide the pork sausage in half and form two burger patties.
Grill the patties for about 5-6 minutes on each side or until the internal temperature is at least 160 degrees. Remove the burgers from the grill and top with the provolone cheese and allow to rest on a plate.
Place your burger buns facedown onto the grill and toast for about 1-2 minutes.
Slather both sides of the toasted buns with a generous amount of the pesto mayonnaise. Then top with the burger, caramelized onions, arugula, and tomato.
