Ingredients

• 1 cup finely chopped unpeeled English hothouse cucumber
• 3/4 cup mayonnaise
• 3 tablespoons prepared white horseradish
• 2 tablespoons finely chopped fresh Italian parsley
• 1 tablespoon finely chopped fresh chives
• 3 tablespoons olive oil plus more for frying fish cakes
• 3 medium carrots, peeled, finely chopped
• 1 2/3 cups finely chopped leeks (white and pale green parts only)
• 2 large eggs
• 6 tablespoons unsalted matzo meal
• 1 3/4 teaspoons coarse kosher salt
• 3/4 teaspoon ground white pepper
• 18 ounces skinless whitefish fillets, cut into 1-inch cubes
• 1 9-ounce skinless salmon fillet, cut into 1-inch cubes
• Lemon wedges
• Fresh Italian parsley sprigs

Instructions

1. Stir cucumber, mayonnaise, horseradish, parsley, and chives in medium bowl to blend. Season sauce to taste with salt and pepper. DO AHEAD: Sauce can be made 1 day ahead. Cover and refrigerate.
2. For fish cakes: Line large rimmed baking sheet with plastic wrap. Heat 3 tablespoons oil in heavy large skillet over medium heat. Add carrots and leeks. Saut&#
3. Line large rimmed baking sheet with plastic wrap. Heat 3 tablespoons oil in heavy large skillet over medium heat. Add carrots and leeks. Saut&#