Heat your oven to 425 degrees Fahrenheit/220 degrees Celsius.
Wash chicken inside and out. Pat it dry. Cut back bone out using kitchen shears or a sharp knife. Save bone in a bag to make chicken stock in the future. Turn chicken over. Press down on breast to flatten chicken.
Season chicken on both sides with 1/2 tsp coarse salt and 1/2 tsp ground black pepper. To a bowl, add oil, vinegar, garlic, 1/2 tsp salt and 1/2 tsp pepper. Mix well and rub all over chicken on both sides including under the skin.
Place chicken on a baking sheet (line with foil if you wish). Place baking sheet on the top rack of your oven. Cook in the heated oven for 45 minutes or until a thermometer inserted into the thickest part of the thigh reaches 165 degrees Fahrenheit or 75 degrees Celsius. Remove chicken from oven and let rest for 10 mins. Cut and serve.