Bring a large pot of water to a boil. Score the bottom of each tomato with an 'X' using a sharp knife. This will help the skin peel off easily after blanching.

Once the water is boiling, carefully add the tomatoes and blanch for about 30-60 seconds, or until the skins start to peel away.

Remove the tomatoes from the boiling water and immediately transfer them to a bowl of ice water to stop the cooking process. Let them cool for a few minutes.

Once cooled, peel the skins off the tomatoes, remove the cores, and chop them roughly. Set aside.

In a large pot, heat the olive oil over medium heat. Add the chopped onion and sauté for about 5-7 minutes, or until translucent. This step builds the flavor base for the sauce.

Add the minced garlic and sauté for an additional 1-2 minutes, being careful not to burn it, as burnt garlic can impart a bitter taste.

Stir in the chopped tomatoes, salt, sugar, oregano, basil, and black pepper. Bring the mixture to a simmer.

Reduce the heat to low and let the sauce simmer uncovered for about 30-40 minutes, stirring occasionally. This allows the flavors to meld and the sauce to thicken.

After simmering, taste the sauce and adjust the seasoning if necessary. If you prefer a smoother sauce, use a blender or immersion blender to puree it to your desired consistency.

Once the sauce is cooked to your liking, remove it from the heat. Stir in the chopped fresh basil for a burst of flavor.

Serve the sauce hot over your favorite pasta, pizza, or use it as a base for other dishes. Enjoy your homemade tomato sauce!