Place the potatoes in a cheesecloth or in a colander and wring, or squeeze by the handful, extracting as much moisture as possible.
In a medium bowl stir the potatoes, onion, eggs, flour and salt together.
In a large heavy-bottomed frypan over medium-high heat, heat the oil until hot. Place large spoonfuls of the potato mixture into the hot oil, pressing down on them to form 1/2 - 1 cm thick patties. Brown on one side, turn and brown on the other. Let drain on paper towels. Serve hot!