Steps

1. Place 1/2 onion in a frying pan and stir-fry over high heat until caramelized. [This is the key!] The more you stir-fry the onion to remove moisture, the more concentrated its sweetness and umami will become.
   🕒 00:43
2. Let the caramelized onion cool down, wrap it, and chill it in the refrigerator. [This is the key!] Chilling in the refrigerator makes the fat less likely to melt when mixed with the ground meat later.
   🕒 01:14
3. Place 20g dried bread crumb (Wheat Gluten) in a mixer and finely crush it. [This is the key!] Compared to breadcrumbs, dried bread crumb absorbs moisture more effectively and helps to lock in the juices.
   🕒 02:13
4. Mix the crushed dried bread crumb with 120g milk and let it sit until the bread crumb has absorbed the liquid and become fluffy. [This is the key!] This will make it easier to mix with the ground meat later.
   🕒 02:43
5. Prepare a bowl over ice and lightly pat the excess drip from 400g ground mixed meat with paper towels. [This is the key!] Kneading while chilling on ice prevents the fat from melting due to the heat of your hands, thus locking in the juices.
   🕒 03:02
6. Add 4g salt to the ground mixed meat and knead thoroughly until it becomes sticky and forms a cohesive mass. [This is the key!] Kneading with salt first helps the ground meat particles to bind together, making the hamburg steak less prone to cracking and less likely to lose its juices.
   🕒 03:27
7. Add 20 shakes black pepper and 5 shakes nutmeg to the kneaded ground mixed meat.
   🕒 04:07
8. Add 45g beef fat and mix quickly to incorporate it evenly. [This is the key!] Bringing the beef fat to room temperature or lightly warming it in a double boiler makes it easier to mix and results in hamburg steaks that are bursting with juice. Any remaining chunks can cause holes when cooked, so mix thoroughly.
   🕒 04:14
9. Add 1 egg and mix, then knead until it comes together.
   🕒 05:06
10. Add the cooled sautéed onion and mix.
    🕒 05:15
11. Finally, add the dried bread crumb (Wheat Gluten) rehydrated with milk and mix everything together. The mixture is now ready.
    🕒 05:23
12. Lightly coat your hands with vegetable oil and divide the mixture into your desired size (approximately 210g to 230g).
    🕒 05:40
13. Toss the mixture back and forth between your hands to remove air bubbles. [This is the key!] If air remains in the mixture, it may burst due to expansion when heated during cooking. Performing this over a tray is safer.
    🕒 06:12
14. Once air is removed, form the mixture into a hamburg steak shape with some thickness, and smooth the surface. [This is the key!] Making it thick helps to lock in the juices, and smoothing the surface prevents cracking during cooking.
    🕒 06:32
15. Chill the formed hamburg steaks in the refrigerator for 1 hour. [This is the key!] Completely chilling the mixture prevents the fat from melting all at once when cooked, allowing it to cook through slowly and lock in the juices.
    🕒 07:12
16. Remove the hamburg steaks from the refrigerator and lightly coat the entire surface with all-purpose flour, tapping off any excess. [This is the key!] Coating with flour helps to prevent juices from escaping and improves sauce adhesion.
    🕒 07:36
17. Add a little extra vegetable oil to a frying pan and, once heated, gently place the hamburg steaks in it.
    🕒 08:03
18. Sear one side until crispy over medium-high heat, then cover and steam-cook. [This is the key!] Cooking over low heat will cause the juices to escape, so cook over high heat to coat the surface and do not touch it until you flip it.
    🕒 08:33
19. Once one side is cooked, flip and cook the other side thoroughly without touching until cooked through.
    🕒 08:59
20. Wipe off any burnt flour residue that floats up during cooking with paper towels.
    🕒 09:04
21. Once both sides are browned, reduce heat to low, add a little water, cover, and steam-cook. [This is the key!] Steaming prevents moisture from evaporating and results in a fluffy texture. Add small amounts of water if it reduces too much.
    🕒 09:21
22. Cook the hamburg steaks until the internal temperature reaches 75 degrees Celsius for at least 1 minute. [This is the key!] If clear juices come out when pierced with a skewer, it may still be undercooked, so be sure to check the internal temperature with a thermometer.
    🕒 09:52
23. Wipe off excess burnt bits and fat from the frying pan used to cook the hamburg steaks. Add 70g red wine and reduce by about 1/3 while allowing the alcohol to evaporate. [This is the key!] Reducing the wine concentrates its umami and adds richness. Scrape the delicious browned bits from the bottom of the pan into the sauce (deglazing).
    🕒 10:55
24. To the reduced red wine, add 35g ketchup, 10g Worcestershire sauce, 10g medium-thick sauce, 2g sugar, 5g honey, and 1 tbsp water. Mix and lightly reduce. Adjust with water if it becomes too thick.
    🕒 11:48
25. Turn off the heat and quickly stir in 15g unsalted butter to emulsify (monte au beurre). [This is the key!] Stirring quickly to prevent separation creates gloss, thickness, and richness.
    🕒 12:02
26. Plate the cooked hamburg steaks, pour the sauce over them, and it's complete.
    🕒 12:28