In a large skillet, heat the olive oil and butter. Add the sliced red onions and carmelize over medium heat for about 20 minutes, stirirng often.
In a large bowl mix the garlic powder, onion powder, black pepper, chili powder, and salt. Add the plant based meat and mix until combined using hands. Form the plant based meat into 4 flat patties.
To make the secret sauce mix together the mayo, ketchup, parsley, fresh lemon juice, and garlic.
Grill the patties on the BBQ for about 4 minutes per side. For the last 1.5 minutes of grilling throw the piece of cheddar cheese ontop of each patty. Place the buns, face side down on the grill for 1-2 minutes until toasted.
Assemble the burgers with secret sauce, arugula, and fresh sliced tomato.