Cut the chicken breast into large, uniform cubes suitable for skewers.
In a medium bowl, whisk together the extra virgin olive oil, dried oregano, garlic powder, sea salt, black pepper, and lemon juice.
Add the chicken cubes to the marinade, tossing well to ensure every piece is coated, and let it marinate for at least 15 minutes.
While the chicken marinates, cut the bell pepper and red onion into large chunks similar in size to the chicken.
Thread the chicken, peppers, and onions onto skewers, alternating between the meat and vegetables.
Heat a grill or grill pan over medium-high heat and lightly brush with a tiny bit of oil if needed.
Grill the skewers for 10-12 minutes, turning every few minutes, until the chicken is cooked through and the vegetables have a nice char.
In a small ramekin, grate the garlic clove into the Greek yogurt and stir to combine for a quick dipping sauce.
Remove the skewers from the heat and serve immediately with the garlic-yogurt sauce on the side.