Yes, if you open all the way you will get a U shape. The area around the flame that is hot is circular because the flame is circular. If you put a hot circular flame in the middle of the V cut, it will make the inside rounded.
Keep it folded as much as possible, but don't let the two halves of the V touch and swipe with your flame. Just like doing a diagonal cut
only 2 at a time that aren't touching.