Whisk together brown sugar, kosher salt, paprika, dry mustard, oregano, freshly ground black pepper, granulated garlic, ground coriander, and onion powder in a bowl. Whisk in mayonnaise and vinegar until sugar dissolves. Cut cabbage into thick slices; cut slices crosswise. Fold cabbage, bell pepper, and red onion into mayonnaise mixture until coated. Let stand 1 hour before serving, tossing occasionally.