Greek Lemon Chicken Skewers with Tzatziki Sauce

Name: Greek Lemon Chicken Skewers with Tzatziki Sauce
Ingredients: 1 1/4 pounds boneless, skinless chicken breasts, trimmed of excess fat; 1 teaspoon salt; 2 tablespoons plain yogurt; 2 cloves garlic, minced (about 2 teaspoons); 1 tablespoon minced fresh oregano (or 1 1/2 teaspoons dried oregano); 1/8 teaspoon freshly ground black pepper; 1 teaspoon lemon juice; 1 tablespoon extra virgin olive oil plus more for the grill; 2 lemons , thinly sliced; 1 cup plain yogurt; 2 cloves garlic , minced (about 2 teaspoons); 1/2 teaspoon kosher salt; 1/8 teaspoon black pepper; 1 tablespoon lemon juice; 1 cucumber , peeled