Sauerkraut: Add the oil to a large skillet over medium heat. Drop in the cabbage and saute for a few minutes until the greens have slightly wilted. Add the remaining ingredients to the pan and cook until the liquid has reduced by half and cabbage is tender but still has a slight crunch. Set aside.
Mustard: Whisk together all of the ingredients in a small bowl and set the sauce aside.
Schnitzel: Set up a breading station using 3plates or pie dishes. To the first dish, add the flour. In the second dish, combine the eggs with the water and whisk them together. In the third dish, toss the bread crumbs with the paprika, garlic powder, onion powder and healthy pinches of salt and pepper, to taste.
Lightly dredged the sausages in the flour, then in the egg wash, and then coat them thoroughly in the bread crumb mixture. Set them aside on a sheet tray.
Heat the canola oil in a large skillet over medium-high heat. Fry the sausages until brown and crispy, about 3 to 4 minutes per side. Transfer them to a paper towel-lined plate to drain.
Slice open each roll lengthwise and stuff them with the fried sausages. Top the portions with some sauerkraut, drizzle with the mustard and serve.