1Unwrap the beef cuts, including flank steak, picanha, sirloin, and bone marrow.
2Cut the flank steak into smaller pieces.
3Extract the bone marrow from the bone using a knife.
4Clean the cutting board.
5Attach the meat grinder to the stand mixer.
6Grind the beef cuts to create ground beef.
7Combine the ground beef with the extracted bone marrow.
8Form the ground beef mixture into patties.
9Prepare a roux by mixing flour, water, and milk in a pan over heat until it thickens.
10Prepare the yeast mixture by dissolving sugar and active dry yeast in warm milk.
11Crack two eggs into a bowl.
12Combine all-purpose flour, salt, the yeast mixture, eggs, and unsalted butter in the stand mixer bowl.
13Mix until a dough forms.
14Place the dough in a greased bowl, cover, and let it rise until doubled in size.
15Divide the dough into equal portions and shape them into burger buns.
16Slice a white onion into thick rings.
17Brush the burger buns with egg wash and sprinkle with sesame seeds.
18Bake the buns in the oven until golden brown.
19Dice the remaining white onion.
20Dice the pickles.
21Prepare the burger sauce by combining mayonnaise, ketchup, mustard, black pepper, and pickle juice.
22Mix until well combined.
23Brush the baked buns with melted butter.
24Heat a griddle and add a small amount of fat.
25Place an onion slice on the hot griddle, season with salt and pepper, and press it down with a burger press.
26Cook until caramelized.
27Add more fat to the griddle and place a beef patty.
28Season with salt and pepper.
29Flip the patty.
30Add a slice of cheddar cheese on top of the patty and cover with a bowl to melt the cheese.
31Toast the burger buns on the griddle.
32Assemble the burger by spreading sauce on the bottom bun, adding the cooked patty with melted cheese, caramelized onion, and topping with the upper bun.