Pre heat the oven to 350 degrees and line a baking sheet with parchment paper.
Make the slaw. In a large bowl, toss the cabbage, carrot, onion, scallion, and ginger together. In a small bowl, whisk the vinegar, oil, mustard, sugar and salt together. Pour the dressing over the cabbage mixture and toss until well coated. Set aside until ready to use.
Without cutting all the way through, slice the roll longways and open it like a book. Spread a generous amount of butter followed by mustard on the inside of the roll.
Heat a cast iron pan or griddle over medium high heat. Add the olive oil and swirl to coat. Add the split sausages to the pan and cook until browned and warmed through; 2-3 minutes on each side.
Line the sausages up on the roll diagonally and cover with the gouda slices. Transfer the roll to the parchment lined baking sheet and bake, open, until the cheese has melted; 7-10 minutes. Pile the slaw on top of the melted gouda and close the roll.
Slice and serve hot or at room temperature!