Prepare the chicken: If you haven't already, cut the boneless, skinless chicken thighs or breasts into uniform 2.5cm (1 inch) cubes. Uniformity in size ensures even cooking. Place the chicken cubes in a large bowl.

Make the marinade: In a separate medium bowl, whisk together the extra virgin olive oil (120ml / 1/2 cup), fresh lemon juice (60ml / 1/4 cup), dried oregano (2 tbsp / 10g), minced garlic (4 cloves), salt (1.5 tsp / 9g), and black pepper (1 tsp / 3g). Ensure the garlic is finely minced or pressed to distribute its flavor evenly throughout the marinade.

Marinate the chicken: Pour the prepared marinade over the chicken cubes in the large bowl. Toss gently to ensure every piece of chicken is thoroughly coated. Cover the bowl with plastic wrap or a lid. Refrigerate for at least 30 minutes, but preferably for 2-4 hours, to allow the flavors to meld and the chicken to tenderize. For best results, do not marinate for more than 8 hours, as the lemon juice can start to break down the chicken texture too much.

Prepare the skewers: If using wooden skewers, ensure they have been soaked in water for at least 30 minutes to prevent them from burning on the grill. Thread the marinated chicken cubes onto the skewers, leaving a small space between each piece to allow for even cooking and browning. Aim for about 4-5 pieces of chicken per skewer, depending on skewer length.

Preheat the grill: Preheat your grill (charcoal or gas) to medium-high heat, around 200°C-230°C (400°F-450°F). If using a charcoal grill, arrange the coals for direct heat. If using a gas grill, set the burners to medium-high. Ensure the grill grates are clean and lightly oiled to prevent sticking. You can oil the grates by dipping tongs into a paper towel soaked in vegetable oil and wiping the grates.

Grill the souvlaki: Place the skewered chicken onto the preheated grill. Grill for approximately 4-6 minutes per side, turning occasionally, until the chicken is cooked through, nicely charred, and has reached an internal temperature of 74°C (165°F). Avoid overcrowding the grill; cook in batches if necessary. Watch for flare-ups and move skewers to a cooler part of the grill if they start to char too quickly.

Rest the souvlaki: Once cooked, remove the chicken souvlaki from the grill and transfer them to a clean plate or cutting board. Tent loosely with foil and let them rest for 5 minutes. This allows the juices to redistribute throughout the chicken, ensuring a more tender and moist result.

Serve: Serve the chicken souvlaki hot, directly from the skewers, or remove the chicken from the skewers. They are excellent served with pita bread, Greek salad, tzatziki sauce, lemon wedges, and rice or roasted potatoes.