Sauté cabbage and green onions in hot oil in a large nonstick skillet over medium-high heat 3 to 5 minutes or until cabbage is wilted. Remove from heat, and stir in dressing.
Spread mustard evenly on 1 side of 6 bread slices. Layer evenly with cheese slices, corned beef, and cabbage mixture. Top with remaining bread slices.
Cook sandwiches on a lightly greased nonstick griddle or skillet 3 to 4 minutes on each side or until golden brown.