1. Scrub and prick the potatoes then bake at 230?C/450F/gas mark 8 for 1 to 1 1/2 hours or until soft. Remove from the oven and leave to cool a little. Halve the potatoes, scoop out the insides and mash until soft and fluffy. 2. Saute the onion, mushrooms, sweetcorn, red pepper and garlic in the butter for a few minutes. 3. Place the potato skins on a baking sheet. Mix together the mashed potato the vegetable mixture, half the cheese and all the chopped tarragon. Season to taste. 4. Pile the mixture back into the potato skins and sprinkle with the remaining cheese. Return the potatoes to the oven, turned down to 190?C/375F/gas mark 5 and cook for about 20 minutes until crisp and golden-brown.