Bring a large pot of water to a boil. Prepare an ice bath by filling a large bowl with ice and cold water.

Score the bottom of each tomato with a small '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 them for about 30 seconds, or until the skins start to split.

Using a slotted spoon, transfer the tomatoes to the ice bath to stop the cooking process. Let them cool for a few minutes.

Peel the skins off the tomatoes. Cut them in half and remove the seeds if desired, then chop them roughly.

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

Add the minced garlic and sauté for an additional 1-2 minutes, stirring frequently to prevent burning. Garlic adds a wonderful aroma and flavor.

Add the chopped tomatoes to the pot along with salt, pepper, sugar, basil, oregano, and balsamic vinegar (if using). Stir to combine all the ingredients.

Bring the mixture to a simmer, then reduce the heat to low. Let it cook uncovered for about 20-30 minutes, stirring occasionally. This allows the flavors to meld and the sauce to thicken.

Once the sauce has thickened to your liking, use an immersion blender to puree the sauce to your desired consistency. If using a regular blender, allow the sauce to cool slightly before blending in batches.

Taste the sauce and adjust the seasoning if necessary. You may want to add more salt, pepper, or herbs based on your preference.

Serve immediately over pasta, use as a pizza sauce, or store in an airtight container in the refrigerator for up to a week. This sauce can also be frozen for longer storage.