Cook onion in butter and olive oil in a medium skillet over medium heat 5 min, stirring frequently; cover, and cook 5 min. Uncover, and cook 3 more min or until soft and golden. Set aside.
Beat cream cheese at medium speed with an electric mixer. Stir in mayo and next 4 ing. Fold in caramelized oinion and salmon. Cover and chill.
Serve dip with chips or bread.