In a bowl, mix the ground pork with all the seasonings until well combined. Adjust salt and spices to taste.
Heat a small skillet, cook a little of the pork mixture to taste it, and adjust seasonings if needed.
In a skillet over medium-high heat, melt the butter, add sliced onions, and sprinkle with a pinch of salt.
Cook the onions, stirring occasionally, for 30-60 minutes until they’re golden brown and caramelized.
Add the sauerkraut and beer to the onions, cooking for 5 minutes until the liquid reduces.
Shape the pork into patties about 4 inches wide and 1 inch thick.
Heat a pan over medium-high heat with a little oil and cook the patties for 4-5 minutes on each side until fully cooked.
Toast the pretzel buns, spread mayo and mustard on them, then layer on the burger, caramelized onions, sauerkraut, and cheese. Top with the other half of the bun and enjoy!