Photo and recipe courtesy of Dairy Farmers of Wisconsin.
Place potatoes in pot and cover with cold water; add kosher salt. Bring to a boil and then turn off heat.
Let stand for 20 minutes, covered. Remove potatoes from water and let stand until cool enough to handle.
Slice into 1/8-inch thick slices. Heat skillet over medium-high heat; add canola oil.
Add sausages and fry until browned; remove to plate.
Return pan to heat and add potato slices and onions.
Fry with a pinch of salt and pepper for 5–6 minutes, or until onions are translucent and potatoes are lightly browned.
Cut sausages in half lengthwise and add to potatoes and onion mix.
Heat another skillet over medium heat, spread butter on one side of bread slices and place 4 slices, butter-side down, in skillet.
Top each slice with 2 slices edam cheese, 2 tablespoons sauerkraut, 2 halves of sausage, a spoonful of the potato mixture, and 2 more slices edam cheese, in that order.
Place a piece of bread on top of each, butter side-up.
Grill sandwiches until bread is golden and cheese is melted, turning once during grilling.
Serve with mustard on the side.