If you are looking for this requirement only for a particular local action, then you can try using modal dialog which best suits for it. In the navigation, include an item and on actions launch the flow action as modal dialog.
If not, you can try one of below approaches:
1. On the button click action, Configure Open-Work-By-Handle action and pass pzinskey of the object. This will open the work object in review mode, one more click is required to go back to the assignment.
2. Get the AssignmentKey of the previous screen using and activity, and run 'ProcessAssignment' activity passing the key which will open the assignment in perform mode.