Place all of the ingredients of the marinade in a food processor or blender and blend until smooth.
To cook the steak
Rinse and trim any excess fat from the flank steak and place it in a resealable bag. Add the marinade and massage it to make sure it is well covered. Place it in the refrigerator for about 1-2 hours.
Heat a grill pan over medium high heat. Add a little bit of oil and grill meat for about 8-10 minutes per side or until medium rear to medium. If you want it more well done, cook it for a bit longer.
Place grilled meat over a cutting board and let it rest for about 5 minutes. Then, slice it into thin strips cutting against the grain and serve. You can serve it with salted potatoes, arepas,chimichurri or Colombian green hot sauce.
Nutritional values are approximate and calculated per serving.