Soak the salt cod, immersed in cool water and covered well, overnight in the refrigerator. Change the water 4 times at 3-hour intervals during day hours.
Drain the salt cod and pat it dry, pressing upon the flesh to squeeze out any excess water. Clean thoroughly, removing any skin and bones.
Chop the salt cod into 1/4-inch cubes and put it into a bowl with the eggs, currants, pine nuts, bread crumbs and parsley. Season with salt and pepper, to taste. Mix well to combine.
Using your hands, form the mixture into little round shapes. Coat each shape with the flour, and set aside to rest.
Fill a deep pot no more than halfway with extra-virgin olive oil. Heat oil over medium-high heat until it reaches a temperature of 360 to 365 degrees F. The oil should remain at or around this temperature throughout the cooking process. Working in batches of 6, fry the cod balls until golden brown. Use a slotted spoon or spider to gently drop the balls into the water, being careful not to splatter the hot oil. Using the same spoon or spider, remove the finished balls to drain on paper towels.
Combine onions, lemon juice, chili flakes and mint. Drizzle with extra-virgin olive oil and serve immediately garnished with the lemon.