Display screen or portion thereof with a transitional graphical user interface

Description

FIG. 1 is a first image in a sequence of a display screen or a portion thereof with a transitional graphical user interface showing our new design; and,

FIG. 2 is a second image thereof.

The subject matter in this patent includes a process or period in which an image changes into another image. This process or period forms no part of the claimed design.

The dashed broken lines in the perimeter illustrate a display screen or portion thereof and form no part of the claimed design. The remaining dashed broken lines form no part of the claimed design.

Claims

The ornamental design for a display screen or portion thereof with a transitional graphical user interface, as shown and described.