An American-English Fish Pie

For the smoked salmon

• 1/2 cup sugar
• 1 tablespoon kosher salt
• 2 teaspoons coarsely ground black pepper
• 2 teaspoons mustard powder
• 2 teaspoons grated lemon zest from about 1 large lemon
• 1 pound salmon fillets skin on (you will only need 1/2 lb for the pie, so will have plenty left over)

For the mashed potatoes:

• 2 pounds Idaho or Russet potatoes peeled and cut into 1 to 2 inch cubes
• 6 tablespoons unsalted butter
• 1/2 cup whole milk
• coarse kosher salt to taste
• freshly ground black pepper to taste

For the filling:

• 1/2 pound medium to large shrimp peeled and deveined
• coarse kosher salt divided
• 1/8 teaspoon baking soda
• 1 pound cod or other firm white fish fillets such as halibut, haddock, hake or pollack, skinned, deboned, and cut into 1 1/2 inch chunks
• 4 tablespoons unsalted butter add 2 more tablespoons if using panko
• 2 medium leeks white and light green parts only, washed and finely chopped (8oz after trimming)
• 1/3 cup all-purpose flour
• 1/2 cup dry white wine
• 1 cup whole milk
• 1 cup heavy cream
• 1/4 cup chopped parsley
• 3 tablespoons minced chives
• 2 anchovies finely chopped
• freshly ground black pepper to taste
• 1/2 cup panko breadcrumbs