In a large saucepan, add the oil and saute the onions until soft. Add the garlic and herbs and mix well.
Stir in the courgette and aubergine, cooking for 5-10 minutes.
Add the chopped tomatoes and water, bringing the mixture to the boil.
Once the courgettes and aubergine are soft, add in the sliced peppers and mix well.
Add the mixture into an oven-proof dish.
Slice the potatoes into thin rounds and cover the vegetable mixture with a thin layer of potatoes.
Place in a preheated oven at 180C for 20-30 minutes until potatoes are golden.
Serve with steamed vegetables.