Heat extra virgin olive oil in a large saucepan, then add garlic and onion. Cook on medium-low heat for 5 to 8 minutes, until the onions turn soft and translucent.
In the meantime, prepare bell peppers. Halve them, remove the seeds and the white membrane. Then cut them into strips, a little less than 1/2-inch wide.
Add the peppers to the pan, along with cherry tomatoes, black olives and chili flakes.
Stir for few seconds, then add the tomato paste and water.
Mix everything together and season with salt.
Cover with a lid and let it cook for at least 25 minutes, adding more water if needed. In the end, the peppers should be nice and soft.