Pre-heat the oven to 200 degrees C (450 degrees F)
Melt two tablespoons of butter in a large pot over medium heat. Add in the sliced onion and cook for two to three minutes until soft. Then, add the bratwurst and beer into the pot.
Bring everything to a boil, then cover and cook for 8 to 10 minutes, until the bratwurst are nearly cooked through. Transfer them to a paper towel-lined plate and set aside to cool. Take 1/2 cup of the beer liquid out of the pot and set aside as well.
Bring a big pot of water to a boil on high heat. Once the pot is boiling, add in your 1/4 cup of baking soda and stir until dissolved.
Line a baking sheet with baking paper.
While the water is boiling away, roll out the pizza dough on a flowered surface to a 10 x 6 inch rectangle that is about 1/4 inch thick.
Cut the dough in half horizontally and then cut each half into three long triangles.
Place a dough triangle in front of you, with the short end away from you, and roll out to flatten it slightly. You will want to place a sausage at the long bit near you, along with a big tablespoon of sauerkraut next to the sausage. Roll the sausage and sauerkraut together, like a crescent roll. Repeat with all of the sausages.
Drop two to three of the wrapped bratwursts at a time into the boiling water for about 30 seconds. They will puff slightly. Then use a slotted spoon to remove the sausages from the water and transfer onto the baking sheet to dry. It will take about 5 minutes to dry out.
Brush each of the wrapped sausages with egg yolks and sprinkle with salt.
Bake in your pre-heated oven for 20 to 25 minutes, turning halfway throughout to prevent sticking. Once the dough is a deep golden brawn and the sausage has browned, it is done.
