Step 1:
One side of this paper is darker orange than the other side.
Prefold.

Step 8:
Prefold the edges to the centerline.
Then unfold the folds of step 7

Step 6:
Fold over these two lines.

Step 13:
Fold both ends to the inside (Valley-fold on the same place at the backside of the model)

Step 12:
Repeat step 11.

Step 11:
Press both spots against each other, do the same on the other side.

Step 10:
Fold in half.

Step 9:
Start with the folds in the middle, all lines are prefolded.
Use tape to make the model flat and shiny.

Step 5:
Fold the edges outwards.

Step 7:
Fold both ends to the center.
Then turn the model.

Step 3:
Fold the edges outwards

Step 2:
Fold the edges to the centerline.

Step 4:
Fold over these two lines.

Step 14:
Make the same folds on the backside.
Use tape to keep the model closed.

One slice done..... A few extra folds and you can place it on the edge of a glass

First fold the edge outwards and then inwards, do the same on the other side.

This is a DIY-video for folding the Orange Slices: