Combine all sauce ingredients in a medium bowl. Mix together and set aside in the refrigerator.
Grease and preheat a pan, skillet, griddle, panini maker or whatever you'll use to cook your sandwiches.
Lay out 2 slices of bread and spread a generous layer of sauce on one side of each slice.
Add a slice of cheese to each slice, on top of the sauce.
Add corned beef [about 6-8 ounces] on one slice and top with sauerkraut.
Close sandwich and place in the heated griddle – pan should be heated on medium. Cook for about 4 minutes per side, until bread is golden brown and the cheese is melting.
Allow the sandwich to cool for a few minutes before digging in.