Heat 3 tablespoons oil in a large frying pan on medium high heat.
While the pan is heating, squeeze out as much moisture as you can from the grated potatoes. It is easiest to do this with a potato ricer, using it much like you would a garlic press, except you don't force the potatoes through the ricer. You just press out the moisture. If you don't have a ricer, use paper towels to squeeze out as much moisture as you can from the grated potatoes.
When the oil in the pan heats up to the point of shimmering, but not smoking, add the grated potatoes, spreading them out along the bottom of the pan. The potatoes should not be too thick in any one place, no more than a half inch thick.
Sprinkle some salt and pepper on the potatoes.
After a few minutes, lift up one edge of the potatoes and see how done they are. If they have fried to a golden brown they are ready to flip.
Use a large spatula to flip the potatoes over all at once, or divide the large potato cake into halves or quarters and flip.
Continue to cook until they are golden brown on the bottom.