Bring a medium size pot of water to boil. Using a knife, cut a small X under each tomato and boil in water for 10-20 seconds, until skin breaks a little and looks easy to peel off. Plunge in cold water for a second.
Peel off the skin, cut each tomato into quarters and take out the seeds and core (it doesn’t have to be perfect, take off as much as you can).
Cover a sheet tray with parchment paper (aluminum is also fine), add tomatoes and garlic. Pour the olive oil over them, sprinkle a little coarse salt and toss with your hands. Cook for about 2 hours, turning them over every half an hour to prevent them from burning.
The tomatoes are ready when they’re shriveled and very slightly charred.