• NOTE: This all happens very quickly and over high heat. Read all the instructions carefully before beginning so you have everything ready.

For the filling

• Mezcla la carne con las especias, sal y pimienta y reserva.
• Preheat a cast-iron skillet over high heat. You can also use a flat grilltop.
• Once it's smoking hot, add vegetable oil and the onion. Mix constantly until slightly golden, it should take a couple of minutes.
• Remove the onion, make sure the pan is still very hot, add more oil and place the ground beef on top.
• Use a dish or burger press to weigh down the meat. Let it become golden for a couple of minutes without moving it around.
• After this time, start chopping the meat with a spatula inside the pan until you have small pieces. You want to do this quickly to prevent the meat from drying.
• Add the onion back in, mix everything together and place the sheets of cheese on top. Give them 30 seconds to melt and mix once again. Remove from the heat.

To assemble de sandwich

• Toast the bread on the inside and outside in a pan over medium heat with a bit of butter.
• Spread mayonnaise on the base of the bread, then add ketchup, lettuce and tomato. Don't forget to add salt.
• On top, add the meat from the skillet and close the bread.
• Optional: for that New York feel, you can wrap the bread in aluminium foil and let it rest like this for a couple of minutes.