Heat 1 teaspoon olive oil in a large skillet over medium heat. Add the cabbage and green onions and sauté for 3-5 minutes until cabbage is wilted. Remove from heat and stir in the salad dressing.
For each sandwich, spread mustard on just one side of 1 piece of the bread, then place on a lightly greased griddle, mustard side up.
Carefully pile on the cheese, corned beef, and coleslaw, then top with another slice of bread.
Cook for 3-4 minutes on each side or until the cheese is melted and the bread is nicely toasted.
