In a large bowl, combine the olive oil, the lemon juice, oregano, lemon zest, half the minced garlic, salt, and pepper, and mix.
Add the chicken, zucchini, tomatoes, and mushrooms to the bowl, mix well so all ingredients are well coated, and then cover and refrigerate for 10 minutes.
In the meantime, preheat the grill to medium high heat or the oven to 375 degrees.
Now take chicken and vegetables out, and place on skewers, alternating chicken and vegetables.
Place on the grill, turning every 2-3 minutes, cooking a total of approximately 10-15 minutes, or place in the oven, turning every 10 minutes, cooking approximately 30-40 minutes. Serve and Enjoy.