Make the Chimichurri Sauce by combining chopped herbs, minced garlic, red wine vinegar, olive oil, salt, and crushed red pepper in a bowl. Let sit for 15 minutes.

Prep the filet mignon steaks by seasoning with salt and pepper, then grill at high heat for about 5 minutes on each side for medium-rare.

After grilling, let the steaks rest under aluminum foil for 10 minutes, then slice thinly against the grain.

Warm the corn tortillas on the grill for about 30 seconds or in the microwave for 20-30 seconds until soft.

Assemble the tacos starting with a tortilla, then add sliced steak, chimichurri sauce, sweet corn, crumbled feta, and pickled onions.

Serve the assembled tacos with fresh lime wedges on the side.