Season the chicken breast evenly with sea salt, black pepper, and dried oregano.
Heat a grill pan or skillet over medium-high heat and cook the chicken for 6-7 minutes per side until the internal temperature reaches 165°F.
While the chicken cooks, finely mince the garlic clove.
In a small bowl, whisk together the Greek yogurt, minced garlic, and lemon juice until smooth.
Dice the cucumber into bite-sized pieces and halve the cherry tomatoes.
Spread the garlic-yogurt mixture onto the base of a plate or shallow bowl.
Slice the cooked chicken into strips and place them over the yogurt.
Arrange the cucumber and tomatoes around the chicken, drizzle with olive oil, and sprinkle with crumbled feta cheese before serving.