Preheat grill to medium high.
Season the burgers with salt and pepper and place onto the hot grill. Once you get a nice char and sear, flip the burger and slather with BBQ sauce to glaze and caramelize.
To build with buns:
Spread BBQ sauce on the bottom bun. Now top with lettuce or arugula. Add the burger, followed by the tomato. Drizzle a bit more BBQ sauce, and top with a hefty amount of fried onions. Smear Dijon mustard on the lid of the bun.
To build as a lettuce wrap:
Place burger onto one of the pieces of lettuce. Now add the tomato, followed by a drizzle of BBQ sauce. Top with the fried onions and place a piece of lettuce on top. Carefully tuck the lettuce lid under the wrap to make it a bit easier to eat.