I looked it up on BA, and it appears to be an imperial witbier. Also, the name is spelled "Thick White Freeks" on BA and RB, so it's hard to find under the OP's spelling.
The few reviews I read didn't reference sourness, so I don't know that they did a sour mash. I'm guessing the wheat and the orange or lemon zest gave it that tartness.
But my advice would be to take a standard witbier recipe, scale up the grain bill to 8.5% ABV, and see what you get.