Peel and slice potatoes into pieces about 1/8-inch thick. Fry potatoes in canola oil in a large skillet until light golden brown on both sides. Remove fries from pan and drain on paper towels to absorb any excess oil.
Toss fries in a bowl with salt, feta, oregano and red wine vinegar until well-coated. Transfer fries to serving bowl and top with feta pieces remaining in bowl. Serve immediately.