Heat the oven to 190 C gas 5. Finely slice the potatoes and roughly layer over the base of an oiled roasting tin ( use the 1 tbsp olive oil).Add 250 ml water, season with salt and pepper then cover with foil and bake for 30 minutes.
Combine the canned tomatoes with the extra virgin olive oil, garlic, oregano, capers, half the chopped parsley and sea salt and pepper.
Remove the foil and pour the tomato mixture over the potatoes. Cut the cherry tomatoes in half and scatter on top.
Bake for a further 30 minutes until the potatoes are tender and starting to crisp at the edges. Scatter with the remaining chopped parsley and serve.