To make the sauce, heat olive oil in a large saucepan over medium heat until shimmering. Add garlic, oregano, and red pepper flakes and cook, stirring, until softened and aromatic, about 1 minute. Add tomatoes and juices from the can and break up them into fine chunks. Stir in sugar. Bring to a bare simmer and allow to cook for about 15 minutes to let flavors meld. Season to taste with salt. Set aside and allow to cool slightly.