Preheat oven to 375 degrees F. Line a baking sheet with parchment paper, set aside.

In a large bowl, combine together the ground sirloin, ground pork, Worcestershire sauce, salt, pepper, garlic powder, and 1 tablespoon yellow mustard until evenly mixed through. Divide into 4 equal pieces and then shape each portion into a very large burger patty, placing on a plate or baking sheet. Continue shaping the rest of the patties.

Place a large griddle pan or grill pan over medium-high heat. Once very hot and smokey, grease with a bit of canola oil. Cook the patties, in batches (depending on how big your pan is) for about 2 to 4 minutes on the first side, or until charred and browned. Flip over and continue to cook for another 2 minutes. We're not trying to cook them all the way at this point, because they'll continue to cook in the oven. Transfer to a plate or baking sheet and continue cooking the rest. Let cool to room temperature.

Working with one sheet of puff pastry at a time, cut it in half. Roll out each half slightly to make them larger. Spread the center of each half with mustard and ketchup. Place two full slices of bacon in the center of each, you might have to cut the bacon in half so you'll end up with four half slices for each one. Top with a slice of cheese, and a few pickles. Place the cooled burger on top and then wrap the puff pastry over everything.Turn over and place on the prepared baking sheet. Repeat this with the second puff pastry sheet and remaining burger ingredients.

Brush the tops of each with egg wash and sprinkle with sesame seeds. Bake until golden brown and puffed, about 25 to 30 minutes. Remove from oven and let cool slightly.

In the mean time, to make the sauce, combine the mayo, relish, ketchup, mustard, hot sauce and a pinch of salt and pepper in a medium bowl.

Serve the wellingtons on top of lettuce and tomato, and special sauce on the side. Enjoy!