Place all ingredients, except the flank beef (arrachera), in a blender and blend very well at medium-high speed for about 3 min. Use the resulting liquid to marinate the arrachera.
Pour the marinade into a Vesta Vertical Vacuum Pouch, followed by the arrachera, then seal the pouch with the (Vesta V40 Vacuum Sealer) and leave to marinate in the refrigerator for a minimum of 8 hours.
After 8 hours, remove the pouch containing the arrachera and submerge it in a container/Pot filled with water to the ¾ mark; also add theVesta Immersion Circulator or other sous vide cooker and set it to a temperature of 167°F (75°C) for 25 minutes.
Once time is up, remove the pouch containing the arrachera from the water.
Heat the Griddle / Comal / Frying pan on a stovetop at high heat and add a little vegetable oil to the Griddle / Comal / Frying pan.
Open the pouch, remove the arrachera and sear both sides of them arrachera on the Griddle / Comal / Frying pan for no more than 2 minutes.
Once the meat is ready, take it off the heat and serve.