Crispy Fish Sandwiches

New England seafood shacks sure know how to make the most of the white fish caught in the cold, deep waters of the North Atlantic. They dunk the fillets in a thick batter, deep-fry them until they’re crispy and golden brown, and load them onto a toasted bun with tender lettuce and a smear of tartar sauce. It’s a quintessential coastal sandwich that’s all about the succulent fish and its shatteringly crispy coating.

The fish is so good because the batter creates a physical barrier that protects the delicate fillets (haddock, cod, and halibut are popular choices for their large, sturdy flakes) from the hot oil and mitigates moisture loss. As the batter crisps and browns, the fish inside gently steams to moist, tender perfection. 

After reviewing our existing recipes for deep-fried fish, I narrowed the ingredient list for my batter to equal parts all-purpose flour and cornstarch, beer (for its carbonation and malty sweetness), baking powder, and salt. The flour and cornstarch would play complementary roles: The proteins in the flour would help the batter fuse to the fish and also brown deeply, and the cornstarch, which doesn’t cling or brown as well as flour, would help the batter crisp up nicely. Cornstarch also can’t form gluten, so it doesn’t turn tough. The baking powder would assist in developing a light, airy crust, as would the beer.

After letting the batter rest for 20 minutes so that the starch could fully hydrate, I dunked four haddock fillets into the mixture and fried them in 375-degree oil (our preferred temperature for frying fish) for about 4 minutes per side. As the pieces sizzled in the oil, carbon dioxide from the beer and baking powder started to escape, followed by steam from the beer, leaving hundreds of tiny pockets in their wake and creating a sturdy, lacy structure that became pleasingly crispy as it hardened.

To complement the crispy fish, I whipped up a tangy tartar sauce with capers, shallot, and sweet pickle relish mixed into mayonnaise and spiked with Worcestershire sauce. I spread the sauce onto a toasted brioche bun and topped it with the fish and some tender lettuce. This was a mighty fine representation of a mighty fine sandwich.