Peel and cut root vegetables into coarse pieces and toss with a bit of olive oil, season with salt and place them in a roasting pan. Place the chicken on top and add slices of lemon, chopped garlic, and rosemary on top. Drizzle a bit with olive oil, lemon juice, and salt. Bake in a preheated oven at about 175 degrees Celsius (347 degrees Fahrenheit) for about 1 hour until the chicken is cooked through. Place the chicken on a cutting board and give the root vegetables a blast on high heat for a few minutes until they are well browned. Carve the chicken and serve with the root vegetables, tzatziki, and green salad.