Greek Chicken Bowl with Tzatziki

Name: Greek Chicken Bowl with Tzatziki
Ingredients: 4 cups romaine lettuce ( torn, optional: any greens you like); 16 cherry tomatoes ( halved); 1 red pepper ( chopped); ½ cup cucumber ( chopped (or any other fresh vegetables you like)); ¼ cup red onion ( chopped); ¼ cup feta cheese ( crumbled); ½ cup tzatziki; 1 tbsp grapeseed oil (for frying); 1 pound ground chicken; 3 cloves garlic ( diced); 1 medium yellow onion ( minced or crushed); 4 tbsp balsamic vinegar; 4 tbsp lemon juice; 2 tsp lemon zest; 2 tsp dried oregano; 1 tsp cumin powder; 1 tsp dried basil; ¼ tsp salt ( to taste); ¼ tsp black pepper ( freshly ground); 1½ tsp corn starch