- Prep the following ingredients: 1) Finely chop the onion, carrot, celery and garlic. 2) Halve the baby plum tomatoes. 3) Slice the sweet pointed peppers.
- Heat the extra-virgin olive oil in a medium saucepan over medium-low heat. Add the onion, carrot, celery and garlic and season sea salt and some freshly-ground black pepper. Cook, stirring occasionally, until very soft, 15 to 20 minutes; you want the veg to cook gently without taking on any colour.
- Turn the heat up to medium-high. Add the halved tomatoes and cook, stirring occasionally, until they soften and release their juices, around 5 minutes. Add the peppers and water, season with sea salt and bring to a simmer. Simmer covered, with the lid slightly ajar, for 5 minutes then simmer uncovered for another 5 minutes.
- Remove the saucepan from the heat; tear and stir in the fresh basil. Taste and season with extra sea salt and freshly-ground pepper, if necessary.
STORAGE: this sauce is best served fresh but will keep well in the fridge for up to 4 days or in the freezer for up to 2 months; defrost in the fridge overnight before heating.