Season the steak well with S&P. Whisk together all other ingredients, pour over beef in a shallow dish. Marinate for 24 hours, turning about 3-4 times.
1 head of garlic
1 pint cherry tomatoes, quartered or halved
Preheat the grill to high. Remove the steak from the marinade and season with a bit more salt and more pepper. Grill, covered, until nicely charred and medium rare, 3 to 4 minutes per side. Remove from the grill and rest 5 to 10 minutes before slicing across the grain. To serve, plate a few pieces of toasted baguette. Top with thinly sliced beef, chimichurri sauce and top with relish.