Add the garlic and cook, stirring, until fragrant, about 30 seconds.
Add the tomato paste and cook, stirring, until it starts to brown and sticks to the bottom of the pot, 3 to 4 minutes.
Stir in the grated tomatoes, oregano and 1 teaspoon black pepper.
Bring to a simmer and cook, uncovered and stirring occasionally, until the sauce is thick and a few shades darker, 3 to 4 minutes.