In a large skillet heat butter over medium heat. Add onions and salt. Cook and stir for 5 minutes. Reduce heat; add cayenne pepper. Cover; cook for 5 minutes. Add cabbage. Cover; cook for 5 minutes, stirring twice. Uncover; increase heat. Add honey and vinegar. Bring to boiling; reduce heat. Cook for 5 minutes, stirring occasionally. Remove; cool. Refrigerate for up to 2 weeks.