Step 1

Melt 2 tablespoons unsalted butter in a large 12-inch skillet over medium heat. Add 1 diced large white onion, 1 teaspoon kosher salt, and 1/4 teaspoon black pepper. Cook, stirring occasionally, until lightly browned and softened, about 15 minutes. Meanwhile, starting at one end of the hot dog, evenly wrap 1 slice bacon around each hot dog; use halved toothpicks to secure the bacon if needed.

Step 2

Transfer the onions to a small bowl and cover to keep warm. Wipe the skillet out with a paper towel.

Step 3

Return the skillet to medium heat. Working in batches if needed, place the hot dogs in the skillet and cook, flipping occasionally, until the bacon is evenly golden-brown all over, 5 to 7 minutes total. Transfer to a large plate and cover to keep warm.

Step 4

Add 8 whole serrano peppers to the pan and cook over medium heat, flipping occasionally, until blistered on all sides, about 5 minutes total. Transfer to the plate with the hot dogs.

Step 5

Pour off any bacon fat in the pan into a heatproof bowl; discard or reserve for another use. Wipe the skillet out with a paper towel. Add 4 split hot dog buns cut-side down to the skillet and cook over medium-low heat until toasted, about 2 minutes per side. Transfer to a plate and repeat toasting the remaining 4 buns.

Step 6

To assemble, spread 1 tablespoon mayonnaise over the cut-side of each bun. Place a bacon-wrapped hot dog (remove any toothpicks first) in each bun. Top with the onions, serranos, diced tomatoes, diced avocado, diced pickled jalapeños, ketchup, mustard, and sour cream as desired.