Special equipment: a 1-quart iSi whipped cream siphon, 3 carbon dioxide (CO2) chargers, 6-cup jumbo muffin pan
In a large bowl, gently mix the ground short rib and chuck. Take a quarter of the mixture and gently form a patty slightly wider than the size of your buns. Repeat, forming 4 equal-size patties. Place the burgers in the refrigerator until chilled, about 30 minutes.
Heat a cast-iron griddle or pan until very hot over medium-high heat. If your griddle is well-seasoned, there is no need to oil it, but if not, drizzle it with a bit of the oil. Season the burgers with salt. Gently place the burgers onto the hot griddle and cook until browned, about 4 minutes on each side for medium-rare, seasoning the burgers again after flipping.
Carefully slice the buns in half. Spread some Burger Goop on the bottom buns and place the patties on top. Top with the lettuce and tomato. Spread more Burger Goop on the top buns and close the burgers. Serve immediately.
Preheat the oven to 400 degrees F. Brush a 6-cup jumbo muffin pan with softened butter.
Combine the potato starch, bread flour, sugar, baking powder, salt, baking soda, milk powder and garlic powder in a large bowl and whisk to combine. Fill a measuring cup with 1 1/2 cups water; add the egg and 2 tablespoons of the melted butter and whisk together. Pour the wet ingredients into the dry. Whisk to combine. Pour the batter into a 1-quart iSi whipped cream siphon and charge it with 3 carbon dioxide (CO2) cartridges. Give it a gentle shake and let the batter rest for 10 minutes.
Give the iSi siphon another shake, then eject the batter from the canister into the prepared muffin pan, filling each cup almost to the top. Sprinkle the dough with sesame seeds. Bake until the tops are golden brown, about 7 minutes. Remove from the oven and, while still hot, brush the tops with the remaining 4 tablespoons melted butter.
Add the chopped chives, ketchup, mayonnaise and Dijon mustard to a small bowl. Finely chop the pickles, capers and parsley together and add the mixture to the bowl. Gently stir to combine. Season with salt.
Adapted from "Inside the Test Kitchen: 120 New Recipes, Perfected" by Tyler Florence © Clarkson Potter 2014. Provided courtesy of Tyler Florence. All rights reserved.