Place the leeks in a large pot and add enough water to cover the leeks by 3 inches.

Bring to a boil over high heat, reduce the heat to low, and simmer uncovered for 40 to 45 minutes, until the leeks are very tender.

Drain the leeks and allow them to cool completely. Squeeze the water from the cooked leeks with your hands, working one handful at a time, or place all the cooked leeks in a cheesecloth bag and wring out the liquid. Transfer the leeks to the bowl of a food processor and process in pulses, just until the leeks are coarsely chopped.

Transfer the leeks to a large bowl. Add the ground beef, eggs, breadcrumbs, salt, and pepper, and mix. Let rest for 20 minutes.

Do a taste test. In a small pan with a little oil, fry a tiny portion of the leek mixture. Taste and adjust the seasoning, if needed.

Moisten your hands to keep the mixture from sticking to them. Use your hands to scoop out about a flat tablespoon of the mixture, shape it into a 1½-inch (4 cm) patty, and pack the mixture down so it won’t fall apart. Place the patty on a plate or tray. Repeat until you have used up all the leek mixture.

Cover the bottom of a medium nonstick pan with olive oil about ¼ inch (6 mm) deep, and bring to a frying temperature over medium heat. You can check the temperature of the oil by dipping the handle of a wooden spoon in it. When the oil is ready, it will gently sizzle and bubble up around the handle.

Line a plate with a paper towel. Working in batches, fry 6 or 7 patties for 2 to 3 minutes on each side, until golden, using two forks to turn them. Take the patties out and let them drain on the paper towel-lined plate. Repeat with the rest of the leek patties, a quarter at a time.

Serve warm or at room temperature, with lemon wedges, if desired. Leftover prassokeftedes can be stored in an airtight container in the refrigerator for up to 4 days. To reheat, warm in the oven at 325°F for 6 to 8 minutes.