Spread butter on the inside of the bagel and grill the buttered sides until toasted.
Dice kimchi and then combine in a bowl with kewpie to make kimchi mayo.
Place the toasted bagel base butter side up on a serving plate. Spread Sriracha along the bread, add beef, kraut, dill, swiss cheese, rocket and pickles. Spread mayo on the inside of the other piece and then add to the top to serve.