I plugged in the heat gun, and got to work. 

I started by burning around the edges of the tortilla.  This gives it a nice halo effect, which serves to frame the face. Especially in the area of his hair, I got the tortilla totally black and burned.  I went a little easier at the top of the tortilla, on his forehead.  I didn't want that getting too dark, but I still wanted a little darkness, to define the edge of the tortilla.

The browning sauce has caramel in it, which sizzles and bubbles when you burn it, turning a satisfying deep black.  Oh, it's cool to watch.