In a mixing bowl, combine 1/4 cup of olive oil, 3 cloves of minced garlic, the juice of one lemon, and salt and pepper. Whisk until well blended. Place the flank steak in a resealable bag, pour the marinade over it, and coat evenly. Marinate for at least 30 minutes at room temperature or up to 4 hours in the refrigerator.

While the steak marinates, make the pesto. In a food processor, add 2 cups of fresh basil leaves, 1/4 cup of pine nuts, 1 clove of garlic, 1/3 cup of grated Parmesan cheese, and the juice of half a lemon. Drizzle in 1/3 cup of olive oil while pulsing until smooth. Season with salt and pepper to taste.

Preheat your grill to medium-high heat (about 400°F / 200°C). Ensure grill grates are clean and lightly oiled to prevent sticking.

Remove the flank steak from the marinade, let excess drip off, and place it on the grill. Cook for 4-5 minutes on one side, then flip and grill for another 4-5 minutes for medium-rare. Adjust cooking time for desired doneness, aiming for around 135°F (57°C).

Transfer the grilled flank steak to a cutting board, cover loosely with aluminum foil, and let it rest for 5-10 minutes to redistribute juices.

Slice the rested steak against the grain into thin strips. Arrange the slices on a platter, sprinkle with burrata cheese, and drizzle the pesto on top. Serve and enjoy!