Step 1

Place 3/4 cup warm water in bowl of a stand mixer; sprinkle with yeast. Stir in barley malt syrup until dissolved. Let mixture stand until yeast is foamy, 5 to 7 minutes. Add flour, beer, butter, and kosher salt; using a wooden spoon or rubber spatula, stir until a shaggy dough forms.

Step 2

Attach bowl and dough hook to stand mixer. Beat on medium-low speed until dough comes together and forms a smooth ball, about 1 minute. Dough should be quite firm and may be slightly tacky but not sticky. If dough is sticky, add flour, 2 tablespoons at a time, and beat until dough is smooth. If dough is too dry, add water, 1 teaspoon at a time, and beat until smooth.

Step 3

Increase mixer speed to medium-high, and beat until dough is smooth and elastic, 5 to 7 minutes. Transfer dough to a large bowl greased with cooking spray; turn to coat. Cover with plastic wrap, and let dough rise in refrigerator until almost doubled in size, at least 8 hours or up to 24 hours.

Step 4

While dough rises, preheat oven to 300°F. Spread baking soda in a small glass or ceramic baking dish, and bake in preheated oven 1 hour. Remove from oven, and let cool completely, about 10 minutes. Store cooled baking soda in an airtight container at room temperature until ready to use.

Step 5

Turn dough out onto an unfloured work surface, and firmly press down to deflate. Cut dough into 8 portions. Working with 1 portion at a time and keeping remaining dough covered, pat dough down with your fingertips to form a 3 1/2- by 5 1/2-inch rectangle. Beginning on one long side, roll dough up tightly, forming a loaf shape; pinch seam together on bottom of loaf.

Step 6

Shape each loaf into a rope by rolling it against the work surface with your palms, applying mild pressure and working from the center outward. (If you need more friction, moisten work surface with a few drops of water, dispersing it evenly with your hands.) Continue rolling until dough rope is 14 to 16 inches long and begins to shrink back toward middle. Set dough rope aside, and cover. Repeat process with remaining 7 dough pieces.

Step 7

Line 2 large baking sheets with parchment paper. Return first rolled dough rope to work surface, and continue rolling rope to a length of about 30 inches, leaving middle about 1 inch in diameter and tapering ends by applying a little more pressure as you work your way out. Shape 30-inch dough rope into a U shape, positioning ends of the U pointing away from you. Holding one end in each hand, lift and cross ends over each other about 5 inches down from ends. Cross ends again, passing ends to opposite hands, creating a twist in the dough.

Step 8

Holding ends and maintaining twist, fold ends toward bottom of U. Allowing for a 1/4 inch overhang on each side, press ends into bottom of U at 4 o’clock and 8 o’clock. Gently transfer shaped pretzel to prepared baking sheet; cover loosely with plastic wrap. Repeat with remaining dough ropes, working in the order in which they were rolled, spacing shaped pretzels 1 inch apart on prepared baking sheets.

Step 9

Let covered pretzels rise in a warm place until puffy and increased in size by half, 30 to 45 minutes. Meanwhile, preheat oven to 500°F with racks in upper third and lower third positions. Stir together egg and milk; set egg wash aside.

Step 10

Place baked baking soda in a wide stainless steel (nonreactive) saucepan, and add 6 cups tap water. With range hood vent running on high, bring mixture to a gentle simmer over high, stirring gently to dissolve baking soda. Reduce heat to low, and maintain a very gentle simmer. Using a large skimmer or fish spatula, gently place 1 or 2 pretzels in alkaline water. Cook 20 seconds, carefully flipping after 10 seconds. Using skimmer, lift pretzels from alkaline water, allowing excess to drip off, and transfer to a parchment paper–lined baking sheet, placing at least 1 inch apart. (Pretzels will be wrinkly.)

Step 11

Wearing rubber gloves, reshape pretzels on baking sheet as needed. Repeat with remaining pretzels. Quickly brush tops and sides of pretzels with egg wash, and sprinkle with flaky sea salt.

Step 12

Immediately bake pretzels at 500°F until deep mahogany in color, 9 to 12 minutes, rotating pans from front to back and top to bottom halfway through baking time. Transfer pretzels to wire racks, and let cool about 10 minutes before serving.