3 pounds russet potatoes (about 4 large potatoes), peeled, ends and sides squared off, and cut lengthwise into 1/2 inch by 1/2-inch fries
3 quarts peanut oil (or canola oil), plus 1/4 additional cup
1 1/2 cups all-purpose flour
1/2 cup cornstarch
1/2 teaspoon cayenne pepper
1/2 teaspoon paprika
1/8 teaspoon ground black pepper
Table salt
1 teaspoon baking powder
1 1/2 pounds 1-inch-thick cod filletor haddock cut into eight 3-ounce pieces
1 1/2 cups beer (12 ounces), cold
1/2 Cup Mayonnaise
1 Tablespoon White Wine Vinegar
1 Tablespoon Caper Berries, roughly chopped
1/2 Tablespoon Prepared Horseradish
2 Teaspoons Dijon Mustard
Kosher Salt and Pepper to taste
1. Place cut fries in large microwaveable bowl, toss with 1/4 cup oil,
and cover with plastic wrap. Microwave on high power until potatoes
are partially translucent and pliable but still offer some resistance
when pierced with tip of paring knife, 6 to 8 minutes, tossing them
with rubber spatula halfway through cooking time. Carefully pull back
plastic wrap from side farthest from you and drain potatoes into large
mesh strainer set over sink. Rinse well under cold running water.
Spread potatoes onto kitchen towels and pat dry. Let rest until room
temperature, at least 10 minutes and up to 1 hour.
2. While fries cool, whisk flour, cornstarch, cayenne, paprika,
pepper, and 2 teaspoons salt in large mixing bowl; transfer 3/4 cup of
mixture to rimmed baking sheet. Add baking powder to bowl and whisk to
combine.
3. In heavy-bottomed Dutch oven, heat 2 quarts oil over medium heat to
350 degrees. Add fries to hot oil and increase heat to high. Fry,
stirring with mesh spider or slotted metal spoon, until potatoes turn
light golden and just begin to brown at corners, 6 to 8 minutes.
Transfer fries to thick paper bag or paper towels to drain.
4. Reduce heat to medium-high, add remaining quart of oil, and heat
oil to 375 degrees. Meanwhile, thoroughly dry fish with paper towels
and dredge each piece in flour mixture on baking sheet; transfer
pieces to wire rack, shaking off excess flour. Add 1 1/4 cups beer to
flour mixture in mixing bowl and stir until mixture is just combined
(batter will be lumpy). Add remaining beer as needed, 1 tablespoon at
a time, whisking after each addition, until batter falls from whisk in
thin, steady stream and leaves faint trail across surface of batter.
Using tongs, dip 1 piece fish in batter and let excess run off,
shaking gently. Place battered fish back onto baking sheet with flour
mixture and turn to coat both sides. Repeat with remaining fish,
keeping pieces in single layer on baking sheet.
5. When oil reaches 375 degrees, increase heat to high and add
battered fish to oil with tongs, gently shaking off excess flour. Fry,
stirring occasionally, until golden brown, 7 to 8 minutes. Transfer
fish to thick paper bag or paper towels to drain. Allow oil to return
to 375 degrees.
6. Add all fries back to oil and fry until golden brown and crisp, 3
to 5 minutes. Transfer to fresh paper bag or paper towels to drain.
Season fries with salt to taste and serve immediately with fish.