Melt 2 tablespoons of butter in a large nonstick skillet over medium heat. Add onion and salt and cook for about 6 minutes or until very tender and beginning to caramelize, stirring occasionally.  Add apple and cook for 1 minute.  Add cabbage and cook about 8 minutes or until cabbage is tender-crisp, stirring occasionally.

Combine brown sugar, cider vinegar and Dijon mustard and add to cabbage mixture.  Cook, stirring frequently about 3 minutes or until cabbage is desired tenderness.  Stir in remaining 1 tablespoon of butter, until melted, and caraway seeds.