Preheat griddle to 375-400°F.
When the griddle is hot, add the frying oil. You will need about 4-5 tablespoons, or enough to shallow fry the frozen french fries. Allow the oil to heat up (should take only a few seconds).
When the oil is hot, use tongs or your hands to place the frozen french fries in the oil in a single layer. *Don't just dump the entire bag of frozen fries on the griddle at once, because the drastic temperature change may cause your griddle top to warp. Be careful because the oil tends to spatter upwards and could burn your hand.
Once placed in a single layer, allow the french fries to cook undisturbed for about 4-5 minutes. When a slight golden brown color develops on the first side, use your spatula to flip and turn the fries. Continue cooking for an additional 6-8 minutes, turning the fries a few times until they reach your desired level of crispiness.
Transfer the crispy fries to a large bowl or plate lined with paper towels. Toss the fries a few times so that the paper towels can soak up the excess oil.
Immediately season with salt, seasoned salt, or your favorite french fry seasoning.
Serve the griddle french fries hot with ketchup or your favorite fry dipping sauce.