Before cooking sprinkling the aubergine with salt will draw out any bitterness. Place in a colander and leave for fifteen to twenty minutes then rinse with cold water and pat dry with kitchen paper.
Heat your oven to 425 F / 220 C / Gas Mark 7. Rub the potatoes with the oil, place on a baking tray and sprinkle with salt. Place the tray on the top shelf of the oven and bake for twenty minutes.
Turn the oven down to 375 F / 190 C / Gas Mark 5 and cook for another three quarters of an hour to an hour until the skin is crisp and the inside is soft.
For the Ratatouille
Cut the aubergines into chunks the size of your thumb tip. Place them into a colander and generously sprinkle with salt. After twenty minutes rinse with cold water and pat dry with kitchen paper.
Wipe and slice the courgettes and peel the onions before cutting into one-centimetre pieces.
De-seed the peppers and remove the stalks then cut into one-centimetre pieces.
Pour the oil into a large casserole dish and add the onion. As the potatoes are cooking roast the onions in the oil until soft and brown on the edges.
Add the aubergines, stir, and roast for five minutes. Add the peppers and courgettes and return to the over for another ten minutes.
Add the tomatoes, garlic, sugar and herbs and season generously. Return to the oven and cook for fifteen to twenty minutes. Stir occasionally.
Remove from the oven and allow to cool slightly. To serve split the potatoes into quarters and spoon in some of the ratatouille. Garnish with a little extra olive oil and basil.