Thinly slice the yellow onion into half-moons.
Heat the olive oil in a non-stick skillet over medium-low heat; add the onions, sea salt, and black pepper.
Sauté the onions for 12-15 minutes, stirring occasionally, until they are soft and golden brown, then remove from the pan.
Tightly wrap one slice of center-cut bacon around each chicken hot dog, securing the ends with toothpicks if necessary.
In the same skillet over medium heat, sear the bacon-wrapped hot dogs for 8-10 minutes, rotating frequently until the bacon is crispy and the dogs are heated through.
While the dogs cook, lightly toast the whole wheat bun in a toaster or under a broiler.
Split the toasted bun and spread the Dijon mustard evenly on both sides.
Place the bacon-wrapped hot dogs into the bun and top generously with the caramelized onions.