Wash the tomatoes thoroughly under cold water to remove any dirt or pesticides.

Remove the stems and cut a small 'X' at the bottom of each tomato. This will help with peeling later.

Bring a large pot of water to a boil. Prepare a bowl of ice water nearby.

Once the water is boiling, carefully add the tomatoes and blanch them for about 30 seconds.

Using a slotted spoon, transfer the tomatoes to the ice water to stop the cooking process.

After a few minutes, peel the skins off the tomatoes; they should come off easily.

Chop the peeled tomatoes into small pieces, removing any tough cores.

In a large pot, heat the olive oil over medium heat. This will help release the flavors of the onion and garlic.

Add the finely chopped onion and sauté for about 5 minutes, or until translucent. Stir occasionally to prevent burning.

Add the minced garlic and sauté for an additional 1-2 minutes, until fragrant. Be careful not to let it brown.

Add the chopped tomatoes to the pot, along with salt, black pepper, and sugar. Stir well to combine.

Bring the mixture to a simmer, then reduce the heat to low. Allow the sauce to cook uncovered for about 20-30 minutes, stirring occasionally. This will help thicken the sauce and develop the flavors.

If you prefer a smoother sauce, use a blender or immersion blender to puree the sauce to your desired consistency.

Taste the sauce and adjust seasoning if necessary.

Remove the sauce from heat and stir in the chopped fresh basil.

Serve the sauce warm over your favorite pasta, pizza, or use it as a base for other dishes.