Wash the tomatoes and cut them into smaller chunks. Blend them in a food processor until smooth. Strain the tomato puree and discard the skin and seeds.

Preheat oil in a large saucepan. Add onion and cook until translucent. Add garlic and cook until it becomes fragrant.

Add the tomato puree to the saucepan. Cook until the mixture boils. Let the sauce simmers down until it becomes thick for about 20-25 minutes.

Season with sugar, salt, black pepper, dried oregano, and dried basil.

Taste the sauce. If it tastes does not acidic enough, you can add tomato paste into the sauce (optional).

Let the mixture cools down completely before using or storing it in an airtight container.