Step 1

Mix mayonnaise, capers, shallot, parsley, tarragon, horseradish, mustard, and cayenne together in a bowl for tartar sauce and refrigerate until needed.

Step 2

Add milk and bay leaf to a saucepan and place the pieces of fish over the top. Season with salt. Bring to a simmer over medium heat, and cook for about 1 minute, stirring occasionally. As soon as the fish firms up, but before it starts to flake apart, turn off the heat and cover. Let sit for 5 minutes before draining. Let cool, about 10 minutes. Refrigerate until needed.

Step 3

Meanwhile, bring a pot of lightly salted water to a boil. Add russet potato and boil until tender but not falling apart.

Step 4

Drain and mash potato in a bowl. Season with salt, black pepper, and cayenne. Add parsley, chives, and lemon zest; add 1 tablespoon tartar sauce mixture. Mix until combined. Flake chilled fish over the top. Mix until combined.

Step 5

Scoop out ¼ of the mixture and form into a patty. Repeat with remaining mixture.

Step 6

Dust cakes with flour on both sides. Brush both sides of cakes with beaten egg. Coat in bread crumbs.

Step 7

Heat oil in a skillet over medium heat. Pan-fry patties in the hot oil until golden brown and heated through, 3 to 4 minutes per side. Drain on paper towels before serving with tartar sauce.