Slice off a piece of sweet potato length wise, so it sits flat on cutting board. Make half inch slices lengthwise. Cut those into fries.
Microwave (covered) two minutes each side or until pliable.
Beat egg white until frothy.
Chop sage. Put half into egg white.
Dip into egg white, but make sure there is no excess on potatoes.
Brush olive oil on parchment paper.
Do not salt potatoes until after baking.
Place potatoes on single layer on baking sheets.
Bake at 450 for 10 minutes. Turn for another 10-15 minutes until cripsy
During last five minutes, add more sage on potatoes.
Salt when potatoes are done.