The general way to cut bitter melon is like this, according to the thickness of the cylinder equal parts of four or six, sliced to remove the white core, and then change the knife according to the desired size and thickness.

There are two general methods:

1

The knife and the countertop 90 ° right angle down the knife, usually cut into a diamond shape. It is thicker.

2

Knife and table angle < 90 ° down the knife, and the horizontal control angle, you can according to their own wishes to cut a different area as well as the thickness of the effect. Vertical and horizontal angle changes can have many different effects.

I guess you are talking about the second one.