Tzatziki Chicken Skewers

Name: Tzatziki Chicken Skewers
Ingredients: 4 tablespoons olive oil; 1 lemon (juiced); 2 tablespoons dried oregano; ½ teaspoon garlic powder; 1 teaspoon salt; 8 boneless skinless chicken thighs ((about 2 pounds) cut into 1” pieces); 2 small zucchinis ((or 1 large) sliced into 1/4” moons); 1 red onion (chopped); 1 pound cherry tomatoes; 1 cup prepared tzatziki (store-bought or recipe as follows); 1 cup Greek yogurt; 1/2 cucumber (seeds removed & chopped fine); 2 tablespoons chopped fresh mint; 4 cloves garlic (finely minced); 1/2 teaspoon salt