For the roast chicken
Preheat the oven to 200 C . Rub the chicken with the marinade inside out and place in a roasting tin. Allow to rest for an hour. Put the onion and lemon wedge inside the abdomen cavity of the chicken. Tie the legs with a cotton kitchen twine. Brush some melted butter on the chicken and place it in the hot oven and bake for 45 mins, basting it every 10 mins with butter turning it round halfway through to attain a golden colour. Remove from the oven and let the roasted chicken rest. Transfer the chicken in another plate and in the same roasting pan pour some wine, and chicken stock or water and heat it to remove all the scrapings. Strain the gravy and return to the flame add salt and pepper to taste, lemon juice and a little honey or sugar and allow it to boil.
Before serving the chicken place it in a plate along with lemon slices and serve with hot gray to be poured over it.
Peel the potatoes and boil in a pan along with a little salt till they are cooked but firm.
In a pan add oil and butter and add the garlic till pale golden add the rosemary and stir for a minute. Add the potatoes and coat them with the herbed oil mixture, allow to cook till soft stirring every now and then till a crust is attained on the surface of the potatoes.