Stir together the Luke warm (barely warm) water, brown sugar and yeast and allow to bubble up, this should take 5 minutes. If it's not getting bubbly, your water may have been too hot or your yeast is bad. You'll have to repeat this step.
15 grams brown sugar, 4 grams active dry yeast, 275 milliliters water
Combine with all other dough ingredients. Knead the dough on the low setting for 8 to 10 minutes using the dough hook.
500 grams all-purpose flour, 10 grams sea salt, 30 grams butter
Cover the dough with a clean linen towel and let it rest while you prep your pretzel pizza toppings.
Cut the Knackwurst into slices, thinly slice the onion (I used about ¼ of a large red onion), drain the sauerkraut. Shred the cheese if you didn't buy a shredded kind.
200 grams emmentaler cheese, 3 Bratwurst, 450 grams sauerkraut, ¼ onion
Divide the dough into quarters and roll out two of the quarters into round circles with about 16 inch (40 cm) diameter.
Place the rolled out pizza circles onto large baking sheets topped with parchment paper or silicone baking mats.
Top in the following order: sour cream, salt and pepper, shredded cheese, sauerkraut, onion rings, mustard, bratwurst.
200 grams sour cream, German mustard
Shape the other 2 dough pieces into long strings, long enough to wrap around the edge of the pizza crust.
Prepare your lye solution in a well-ventilated area (like standing under a vent hood set to high or ideally being outside) because of potential fumes. Add the premeasured lye (it comes in dry granules) into COLD water, not the over way around. At this point, I like to step to the side for about 10 to 15 seconds to let potential fumes evaporate.Then carefully combine with a whisk until the solution is clear.Now add your pretzel strings and leave them in the solution for 5 to 10 seconds, carefully removing them with 2 sets of tongs and placing 2 each on the edge of the pretzel pizza. 12 grams food-grade lye, 300 milliliters water
Optionally top the crust ring with pretzel salt before baking. You could skip adding the salt and add a little shredded cheese onto the crust instead or add nothing at all (Germans don't like a ton of salt on their pretzels and the pizza toppings are already salty enough).
pretzel salt
Bake your pretzel pizza at 355° Fahrenheit or 180° Celsius (convection/Umluft setting) for about 14 to 17 minutes, rotating the 2 pizzas 7 minutes into baking.