There are many versions of these sweet and sour peppers, rather than olives you could use capers, toasted pine nuts or even some raisins stewed at the same time as the peppers so they soak up the juices and become nice and plump. This is a great side dish to go with grilled fish or indeed with cold meats and crusty bread, I've even been known to stir some through some cooked cold pasta for lunch.
Heat the oil on low to medium heat in a large and wide pan the add the garlic and stir around to infuse the oil, you're not looking to brown the garlic so be careful of the heat.
Add the peppers and the chopped rosemary and stir through to cover with all the garlicky oil, continue to cook for 20-30 minutes until they begin to soften and the peppers release all their lovely sweet juices.
Add the sugar, vinegar and dried oregano and continue to cook for a further 5 minutes.
Season the peppers and then taste them for your preferred balance of sweet and sour, add more sugar or vinegar if you like and cook for a few more minutes if you need to.
Allow the peppers to cool to room temperature and then sprinkle with the olives when serving.