Chop the Vidalia onions and sauté them in olive oil over medium heat until soft and lightly caramelized. Let cool slightly.

In a large mixing bowl, combine the ground beef, sautéed onions, breadcrumbs, egg, steak seasoning, and Japanese BBQ sauce. Mix gently until just combined—don’t overwork the meat.

Form the mixture into burger patties, making them slightly larger than your buns to allow for shrinkage during cooking.

Preheat your pellet smoker to 350°F.

Cook the burgers indirect on the smoker for 15 minutes, or until they reach an internal temperature of about 125°F.

While the burgers smoke, melt the butter and brush it onto the sliced burger buns. Place the buns under your oven broiler and toast until golden brown.

Transfer the burgers to a hot charcoal grill and sear for 2 minutes per side to develop a crust and finish cooking.

Remove burgers from the grill and let rest for a few minutes before serving on the toasted buns with your favorite toppings.