Preparation Cook leeks in large saucepan of boiling salted water until just tender, about 8 minutes. Drain very well and cool. Working in batches, wrap leeks in kitchen towels and squeeze out all liquid. Place leeks in processor and blend to coarse paste. Transfer leeks to large bowl. Add 3/4 cup panko, eggs, lemon juice, baking powder, salt, and pepper; blend well. Mix in nuts. Add more panko by tablespoonfuls if mixture is very moist. Shape 3 tablespoons leek-walnut mixture into 1/2-inch-thick patty. Place on plastic-lined baking sheet. Repeat with remaining mixture. Do ahead Can be made 1 day ahead. Cover patties with plastic and refrigerate. Preheat oven to 300°F. Line baking sheet with several layers of paper towels. Pour oil into large saucepan to depth of 1 inch. Attach deep-fry thermometer to side of pan and heat oil to 350°F. Working in batches, fry patties until golden brown, about 4 minutes per side. Transfer fritters to prepared baking sheet to drain. Place baking sheet in oven to keep fritters warm. Divide fritters among plates. Garnish with lemon wedges and serve.
Preparation Cook leeks in large saucepan of boiling salted water until just tender, about 8 minutes. Drain very well and cool. Working in batches, wrap leeks in kitchen towels and squeeze out all liquid. Place leeks in processor and blend to coarse paste. Transfer leeks to large bowl. Add 3/4 cup panko, eggs, lemon juice, baking powder, salt, and pepper; blend well. Mix in nuts. Add more panko by tablespoonfuls if mixture is very moist. Shape 3 tablespoons leek-walnut mixture into 1/2-inch-thick patty. Place on plastic-lined baking sheet. Repeat with remaining mixture. Do ahead Can be made 1 day ahead. Cover patties with plastic and refrigerate. Preheat oven to 300°F. Line baking sheet with several layers of paper towels. Pour oil into large saucepan to depth of 1 inch. Attach deep-fry thermometer to side of pan and heat oil to 350°F. Working in batches, fry patties until golden brown, about 4 minutes per side. Transfer fritters to prepared baking sheet to drain. Place baking sheet in oven to keep fritters warm. Divide fritters among plates. Garnish with lemon wedges and serve.