Slice the top of each vegetable off, but keep it, to use as a 'lid' for each one.  Using a teaspoon, scoop the pulp out, and set aside in a bowl.

Place the hollowed vegetables in a large pan or ovenproof dish.  Season their interiors with salt, pepper and a pinch of sugar.

Process the pulp of all the vegetables, the carrots, onions, garlic, parsley, peppermint and fennel in a food processor or blender.

Put this mixture in a bowl, add some olive oil, water, the rice, salt and pepper.  The quantity of water you add depends on how juicy your tomatoes where. You should get a mixture that is not dry, but it is not overly juicy either. This will be your stuffing.

Fill the vegetables with the rice mixture and cover them with their 'lids'.  Sprinkle with some olive oil and the breadcrumbs.

Peel the potatoes, cut into large pieces, season with salt and pepper and place them between the vegetables.  Any left over stuffing may be spread out over the potatoes and between the vegetables. Don't put it though over the vegetables because it will get dry. For even better results, pour some extra tomato juice in the pan.

Bake in a moderate oven (180 degrees) for approximately an hour, until the vegetables are tender and the rice cooked.