The burgers were juicy and tender with an extremely satisfying crunch through the browned surface. The actual work making the burgers was minimal, but the setup complicated. I cooked these as part of Fried Day at the Instructables lab when we already had both liquid nitrogen and pots of hot oil ready to go.
Here are the abbreviated instructions; go through each step for pictures and more information:
- Mix ground beef with salt to achieve a 0.8% salt concentration, refrigerate for an hour
- Cook beef sous vide to an internal temperature of 131°F
- Freeze the outside of the burgers in liquid nitrogen for 30 seconds
- Fry the burgers in oil at approximately 425°F for 30 seconds
Step 1: Ground beef, salt, make patties
Add salt to make a 0.8% concentration. Fold the salt into the ground beef, form patties with a mass of approximately 180 - 200 g, put them into plastic bags, and add 5 g of a neutral oil.
Step 2: Refrigerate
Step 3: Cook sous vide
Step 4: Freeze with liquid nitrogen
Leave your utensils (in the images, either the strainer or the tongs) in the liquid nitrogen between freezing burgers to keep them cold which will help prevent the burgers from sticking to them.
Step 5: Fry in hot oil
Make sure the oil is hot enough. On the stove top shown in the images, I could only achieve around 425°F by keeping the burner at high and covering the pot.
The objective of frying is to brown the entire surface of the burger through the Maillard reaction. Hand-wavingly, the liquid nitrogen is at approximately -200°C and the oil is at approximately 200°C, so equal time in each leaves the center of the burger just slightly colder than it started and doesn't overcook it.