In a resealable bag, combine flank steak, half of the olive oil, salt, and pepper. Let it marinate for at least one hour or overnight.

Blend parsley, garlic, remaining olive oil, red wine vinegar, salt, and red pepper flakes until smooth but slightly chunky.

Heat your grill to medium-high (around 450°F).

Remove the steak from marinade and grill for about 5-7 minutes per side for medium-rare.

Allow the steak to rest for 5 minutes before slicing against the grain.

Drizzle the grilled steak with chimichurri sauce and enjoy alongside grilled vegetables or rice.