Canola oil, for frying
1⁄4 cup finely chopped flat-leaf parsley
3 cloves garlic, finely chopped
Zest of 1 lemon
2 1⁄2 lbs. russet potatoes, peeled
Kosher salt, to taste
2 12-oz. bottles beer, preferably lager
1 small yellow onion, quartered
2 whole cloves
4 bratwurst (about 3⁄4 lbs.)
4 New England–style hot dog buns
2 tbsp. unsalted butter, melted
Dijon mustard, as needed
1 pint Pickled Cauliflower
1. Pour enough oil into a 12-quart pot so that it reaches a depth of 1". Heat over medium-high heat until a deep-fry thermometer inserted in the oil registers 375°. Make a gremolata by mixing parsley, garlic, and lemon zest in a large bowl; set aside. Over a kitchen towel, julienne potatoes lengthwise using the narrowest setting of a French mandoline. Pat julienned potatoes dry with the towel.
2. Working in 2 batches, fry potatoes in oil until crisp, 6–10 minutes. Using a slotted spoon, transfer fries to a paper towel–lined bowl. Season with salt. (Bring oil to 375° before frying second batch.) Transfer fries to bowl of gremolata; toss to coat fries evenly. (Serve hot or at room temperature.)
3. Build a medium-hot charcoal fire in a grill or heat a gas grill to medium-high. Meanwhile, bring beer, onions, cloves, and 1 cup water to a boil in a 2-quart saucepan. Boil bratwurst in beer until almost cooked through, about 5 minutes. Drain.
4. Grill bratwurst, turning once, until browned, about 6 minutes. Using tongs, transfer bratwurst to a plate. Brush buns with the butter and grill until toasted and golden brown. Serve the bratwurst in the buns, slathered with mustard and garnished with the pickled cauliflower, alongside the fries.