Starting a day ahead, soak the dried cod in cold water for 12 to 24 hours, changing the water several times to remove the majority of the salt. Drain the cod, rinse, and put it in a large pot. Add the milk and enough water to cover by 1-inch; cooking the cod in milk keeps it really moist. Simmer gently over medium-low heat for 20 to 25 minutes, until the cod is tender and pliable. Drain and rinse well, then flake the cod into a bowl with your hands, removing any little bits of skin and bone.
While the cod is cooking, pour 1-inch of water in a large pot fitted with a steamer insert. Add the potatoes and simmer on medium heat for 20 to 25 minutes until very tender. Drain the potatoes, peel off the skins, and mash them well with a potato masher or pass them through a ricer or sieve.
Add the cod to the potatoes, along with the onion, garlic, parsley, cilantro, and eggs. Beat the mixture firmly with a wooden spoon so that it well combined and firm ¿ a spoon should stand up in it. (If you find it too dry, add 1 or 2 tablespoons of milk.) Season with a pinch of pepper and taste for salt - you may not need to add any, as the cod itself retains enough saltiness, in spite of being soaked and boiled. With lightly moistened hands or using 2 tablespoons, shape the cod mixture into egg-shaped balls ¿ you should get about 25. (The cod balls can be covered and refrigerated for up to 1 day before cooking or frozen in a container.)
Heat 3-inches of oil in a deep heavy skillet or pot to 370 degrees F. Add a few of the cod balls at a time to the hot oil, turning them 3 or 4 times to get nicely browned all over. Carefully lift the cod fritters out of the pan with a slotted spoon and place on a platter lined with paper towels to drain. Repeat. Serve hot or at room temperature with lemon wedges.