Wash the tomatoes and pat them dry; arrange them on a baking tray lined with greaseproof paper, drizzle a spoonful of olive oil over them and cook in a preheated oven, at 100 °C, for 2 hours. Remove from the oven and transfer the tomatoes into a bowl. Season them with a spoonful of olive oil, the salt and oregano, and stir; add the chopped chilli pepper, garlic and basil and stir again. After “dressing” them, leave the cherry tomatoes to marinate for roughly an hour. To preserve them: put them into a sterilised glass jar and screw the lid on tightly, put the jar in a saucepan, pour in enough cold water to cover it, bring to the boil and then leave to simmer for at least 20 minutes. Turn off the heat, leave to cool and only remove the jar when the water is cold.