Remove stems from strawberries to form a flat base. Place berries on cutting surface, pointed end facing up. With a sharp knife, carefully slice each berry in half vertically to within a 1/4 inch of base. Cut each half into three wedges to form 6 petals. (Don't slice through the base.) Pull petals apart slightly.
In a small bowl, combine cream cheese, powdered sugar and sour cream; beat until light and fluffy. With a pastry bag and star tip or small spoon, fill strawberries with cream cheese mixture.