Peel the potatoes and rinse to remove any traces of dirt. Put a chopstick or pencil along each long side of the potato so you don't cut through to the counter. Using a sharp knife, cut potatoes almost through cross-wise in 1/8” thick slices. Repeat the same incision from one end of the potato to the other, spacing the cuts uniformly. The idea is to create the look of a fan, which is why you don't cut all the way through the potato.
Preheat oven to 375 degrees F.
Place the potatoes into a large saucepot and cover with water. Add a pinch of salt and cook until just tender. Do not overcook. The potatoes should remain a little hard, as they will continue to cook during roasting.
Drain the potatoes and place them on paper towels to remove excess water.
Mix the flour, garlic, salt and pepper in a bowl and carefully toss with the already blanched potatoes. Place the floured potatoes onto a baking sheet and drizzle with oil. Bake until golden brown, approximately 30 to 40 minutes.
To finish, scoop the potatoes with a slotted spoon onto paper towels to drain any excess oil. Transfer to a serving dish and garnish with a dollop of sour cream and sprinkle parsley.