1. With a small, sharp knife, cut ends off oranges, down to flesh. Set each orange on 1 cut end on a board. Following contour of fruit, cut off wide strips of peel and white membrane from top to bottom, deep enough to reveal orange flesh. Cut oranges crosswise into 1/2-inch-thick slices.
2. Arrange the orange slices and the blueberries in random layers in a wide, shallow bowl.