What happens if you pre-cook (blanch) fresh cut 3/8Inch potatoes 350 degrees, in lieu of the recommended 250 degrees?

Blanching at a higher temp can be done, Five Guys blanches at 345 degrees and finish fries at the same temp. Personally, I think this is part of the reason why guests receive their fries a little darker.

We typically recommend 325 degrees F for blanching (see all Dr. Potato answers on blanching).

The lower blanching temperatures of 250 degrees to 325 degrees allow the potatoes to cook up without turning brown.