Prepare sauce:
In a small bowl, stir together salad dressing and mustard.
Stir in coleslaw; mix well.
Put together sandwiches:
Spread butter on one side of eight pieces of bread.
Turn over four slices of bread (so un-buttered side is up).
(If desired, lay a piece of wax paper on the cutting board to make clean-up easier.)
Layer on:
half the ham
coleslaw mixture
cheese
remaining ham
Top with remaining bread slices, buttered side up.
Grill:
Preheat the grill, but not too hot!
You don't want the bread to burn before the sandwich is nice and hot inside!
Cook sandwiches about 23 minutes on first side.
Turn over, and cook an additional 23 minutes (until golden, and cheese melts).