Prepare the Chimichurri Sauce: In a food processor, combine fresh parsley, cilantro, garlic cloves, red pepper flakes, and red wine vinegar. Pulse until finely chopped.
Gradually add olive oil while blending until the sauce reaches a thick, pourable consistency. Season to taste with salt and pepper. Set aside half for serving.
Cook the Steak: Preheat your grill or skillet over medium-high heat. Rub flank steak with olive oil, then season with salt and pepper on both sides.
Grill or sear the steak for about 5-7 minutes on each side for medium-rare (adjust time as per your doneness preference). Remove from heat and let it rest for 5 minutes.
Slice the steak thinly against the grain.
Warm the Tortillas: While the steak is resting, warm the tortillas in a dry skillet for about 30 seconds on each side or until pliable.
Assemble the Tacos: On each tortilla, layer a few slices of steak, some halved cherry tomatoes, a couple of avocado slices, and a few red onion rings.
Drizzle with the prepared chimichurri sauce and garnish with fresh cilantro.
Serve with the remaining chimichurri on the side for dipping.
Notes
Serve the tacos on a wooden board, accompanied by lime wedges and extra cilantro for garnish. Enjoy!