Heat the olive oil in a large saucepan over medium heat.
Add the crushed garlic and sliced onion and cook, stirring, until the onion is softened, about 3–4 minutes.
Stir in the tomato paste and cook, stirring constantly, for about 1 minute to deepen the flavor.
Add the chopped, peeled canned tomatoes, reduce the heat to low, and simmer uncovered for 8–9 minutes, stirring occasionally, until the sauce thickens.
Season the sauce with salt, black pepper, and sugar, then stir in the chopped basil and cook for another minute to combine.
Taste and adjust seasoning if needed, then remove from the heat and serve or use as desired.