1) Create a black canvas in Photoshop and add white text.
2) Rotate the text layer 90 degrees clockwise and rasterize it.
3) Apply the Wind filter from the left to create fire-like wisps and repeat the filter until satisfied.
4) Rotate the layer back 90 degrees counter-clockwise and use the Liquify filter to distort the wisps and edges to look less perfect like real fire.