Preheat the oven to 400°F.
Place the bratwurst on a foil-lined baking sheet and cook on both sides until nicely browned, about 7-8 minutes per sides to an internal temperature of 155°F using a thermometer.
In a pot of boiling water, cook the pierogies according to the directions on the package. Drain and set aside.
Cook the pretzel in the oven according to the instructions on the package (if making your own follow instructions in recipe)
In a sauté pan over medium heat, warm the sauerkraut. Drain excess liquid before serving.
In a non-stick pan over medium heat, melt the butter and oil together. Once the butter starts to sizzle, brown the pierogies on both sides until they are golden brown.
Serve the bratwurst with sauerkraut and pierogies and pretzel. Serve with mustard. Garnish with scallions.