Place the leeks into a pot and cover completely with boiling water. Place the pot over medium heat and simmer for 45 minutes until the leeks are very tender and cooked through. Reserve ½ cup of the cooking liquid. Drain the rest of the liquid from the leeks. Once the leeks are cool enough to handle, use your hands to squeeze out as much liquid as possible from the leeks and then finely chop the leeks. Place the leeks into a mixing bowl. Add the beef, matzo meal or bread crumbs, parsley, eggs, salt and pepper into the bowl. Use your hands to mix the ingredients until combined well. Take about 1 ½ to 2 tablespoons of the mixture and form it into a patty. Repeat with the remaining mixture, about 18 patties should be formed.

Preheat the oven to 350 ̊. 

Dredge and fry the keftes: Beat three eggs in a wide bowl. Place the flour into a separate wide bowl. Set aside. Place enough oil in a wide pan to create ½ inch layer of oil. Place over medium-high heat. Start dredging the keftes: take one patty and gently place it in the flour, completely coating the patty. Shake it to take off any excess flour. Next, dip the patty into the egg mixture until completely coated and drain any excess egg. Carefully place the patty into the hot oil. Repeat with enough pattys that fit into the pan at once without overcrowding, about 5-6. Fry the keftes on both sides until browned, about 2-3 minutes per side. Transfer the keftes into an oven safe baking dish. Repeat dredging and frying the remaining keftes. 

Make the sauce and bake: Drain all of the oil from the skillet, but don’t wash it. Add the tomato puree and the reserved half cup of the leek water into the pan. Place the pan over high heat and bring the mixture to a simmer, about 5 minutes. Reduce the heat to medium low and cook for another 5 minutes. Carefully pour this sauce over the fried keftes in the baking dish. The sauce should cover the keftes ¾ the way up. Add more water if needed. Cover the baking dish with aluminum foil and transfer into the oven. Bake for 20 minutes. Serve the keftes hot or the next day.