To make the house ketchup, heat a medium Stainless Clad Saucier or Saucepan over medium and add the oil. Add onion and garlic and sweat until softened and tender (but not browned), 5–6 minutes. Stir in the chili powder, smoked paprika, allspice, and cinnamon; cook until fragrant, about 30 seconds.

Add the tomato paste and cook, stirring, until brick red, about 2 minutes. Add the canned tomatoes, vinegar, brown sugar, salt, hot sauce, and black pepper. Stir to combine. Reduce heat to low and simmer uncovered until thickened, about 1 hour.

Carefully puree until smooth using a blender. Adjust seasoning to taste, adding more brown sugar, vinegar, salt, or hot sauce if desired. Transfer 1 cup ketchup to a bowl and whisk in 1 cup water to create the basting sauce. Reserve the rest for serving.

To make the patties, combine the beef, pork, salt, brown sugar, cayenne, black pepper, smoked paprika, oregano, and garlic in a large bowl. Mix lightly with your hands or a spoon until just combined; do not overmix, as this will make the patties tough.

Divide the mixture into 12 equal balls, about 85 g. (3 oz.) each.

To cook the burgers, preheat a Carbon Steel Griddle over medium. Toast the buns cut-side down until golden. Spread a thin layer of house ketchup on both sides of each bun. Set aside, open-faced.

Increase heat to medium-high. Working in 3 batches of 4 patties each, place meatballs on the hot griddle. Top each meatball with sliced onion and smash firmly with a Grill Press to form patties. Cook until crisp around the edges and mostly cooked through, 2–3 minutes. Carefully flip each patty with a Griddle Spatula and lightly brush the tops with the prepared basting sauce. Cook briefly on the second side, about 1 minute, then stack the patties in pairs.

To assemble, place two patties on the bottom half of each bun. Top generously with potato sticks or shoestring potatoes. Close the burgers with the top buns and serve immediately.