Preheat the oven broiler to medium.
Prep the ingredients per instructions above.
For the glaze, place all ingredients in a saucepan over medium heat, stirring until sugar dissolves. Bring to the boil and cook for 2-3 minutes until slightly reduced. Pour glaze into a bowl and toss with corned beef.
Combine the sauerkraut, onion, and dill in a bowl. In a separate bowl combine the mustard, mayonnaise, and honey. Set aside.
Place bagels, cut side up, on a baking tray. Divide cheese among bases of the bagels. Broil for 3-4 minutes until bagels are golden and cheese is melted and bubbling.
To assemble, spoon the mustard mayo over cheese, top with corned beef and sauerkraut mixture, and finish with glazed bun lid.
Serve reuben bagels with sliced apples, nut butter, and iced tea.