Smoked Whitefish Cakes with Cucumber Salsa

Preparation Line 2 large baking sheets with plastic wrap or waxed paper. Cook potatoes in boiling salted water until very tender, about 25 minutes. Drain. Mash potatoes. Transfer 4 cups potatoes to large bowl (reserve remainder for another use). Melt 2 tablespoons butter in heavy large skillet over medium heat. Add onions; sauté until tender, about 10 minutes. Transfer to bowl with potatoes. Cool. Add flaked whitefish to potato mixture; stir to blend. Season with salt and pepper. Mix in egg. Using floured hands, roll mixture by tablespoonfuls into balls; flatten to 1/2-inch thickness. Transfer fish cakes to prepared baking sheets. Melt 1 tablespoon butter with 1 tablespoon oil in large skillet over medium heat. Dust fish cakes with flour. Working in batches and adding more butter and oil to skillet as needed, add cakes to skillet and cook until golden, about 2 minutes per side. Transfer fish cakes to clean baking sheets. (Can be made 1 day ahead. Cover and refrigerate. Before serving, rewarm fish cakes in 350°F oven until heated through, about 8 minutes.) Preheat oven to 350°F. Using 1 3/4- to 2-inch cookie cutter, cut 3 rounds from each bread slice. Place on baking sheets. Bake until lightly toasted, about 10 minutes. (Can be made 6 hours ahead. Cool. Cover and store at room temperature.) Place 1 hot fish cake on each toast round. Arrange on platter. Drain excess liquid from Cucumber Salsa. Spoon small amount of salsa atop each fish cake; serve.

Preparation Line 2 large baking sheets with plastic wrap or waxed paper. Cook potatoes in boiling salted water until very tender, about 25 minutes. Drain. Mash potatoes. Transfer 4 cups potatoes to large bowl (reserve remainder for another use). Melt 2 tablespoons butter in heavy large skillet over medium heat. Add onions; sauté until tender, about 10 minutes. Transfer to bowl with potatoes. Cool. Add flaked whitefish to potato mixture; stir to blend. Season with salt and pepper. Mix in egg. Using floured hands, roll mixture by tablespoonfuls into balls; flatten to 1/2-inch thickness. Transfer fish cakes to prepared baking sheets. Melt 1 tablespoon butter with 1 tablespoon oil in large skillet over medium heat. Dust fish cakes with flour. Working in batches and adding more butter and oil to skillet as needed, add cakes to skillet and cook until golden, about 2 minutes per side. Transfer fish cakes to clean baking sheets. (Can be made 1 day ahead. Cover and refrigerate. Before serving, rewarm fish cakes in 350°F oven until heated through, about 8 minutes.) Preheat oven to 350°F. Using 1 3/4- to 2-inch cookie cutter, cut 3 rounds from each bread slice. Place on baking sheets. Bake until lightly toasted, about 10 minutes. (Can be made 6 hours ahead. Cool. Cover and store at room temperature.) Place 1 hot fish cake on each toast round. Arrange on platter. Drain excess liquid from Cucumber Salsa. Spoon small amount of salsa atop each fish cake; serve.