In a large, deep frying pan on med/high heat; heat oil. Add onion to the pan once it is hot and stir. After 3 or 4 minutes add in the chopped garlic and brown gently. Do not burn. Add drumsticks and brown on each side.
Pour in chicken stock, passatta, veggies and rice. Mix thoroughly.
Turn heat down to low and put the lid on the pan. Simmer gently for 40 - 50 minutes. Stir a few time throughout cooking to ensure the rice is cooking evenly. Add a bit more chicken stock if needed if liquid has been soaked up before the chicken is done.
Check the chicken after 40 minutes to see if they are cooked through and not pink. Once chicken is cooked, turn off the heat. Serve.