Scrub, peel and cut potatoes into 1/3 inch by 1/3 inch thick strips.
Place potatoes in large bowl; rinse several times with warm water.
Fill bowl with cold water and soak potatoes 1 hour.
Drain, pat dry with paper towels, then wrap in kitchen towels to absorb extra moisture.
Attach deep-fry thermometer to side of large deep pot.
Add canola oil and duck fat to pot and heat over medium-high heat to 300 F.
Working in batches, fry potatoes until cooked through but still very pale n color, adjusting heat as neccesary to maintain temperature, about 5 minutes or so.
Using slotted spoon, transfer potatoes to paper towels and drain Allow potatoes to cool.
Reheat oil in pot to between 365 and 370 F.
Working in batches, fry potatoes until deep golden and crisp, about 5 minutes.
Transfer to fresh paper towels; drain Sprinkle with kosher salt and pepper.
Transfer to bowl and serve.