Preheat oven to 200°C / 392°F.
Remove the stems and bottoms of the tomatoes and cut them in half.
Cover a sheet pan or your oven's baking tray with parchment paper.
Lay the tomatoes so their skin is facing upwards.
Drizzle with a good splash of extra virgin olive oil on top. Season the tomatoes with salt and pepper.
Bake the tomatoes for 15-20 minutes until they get a nice roasted color and their skins start to come off.
Remove the pan from the oven and set it aside.
In a medium-sized cooking pot heat a generous splash of olive oil over medium-high heat. Add the onion and saute until completely soft and golden in color.
Then add the tomatoes to the pot along with their juices from within the pan.
Drop the heat to medium. Add the tomato paste and sugar and cook for 2-3 minutes stirring with a wooden spoon and mushing the tomatoes as you stir.
Then add 2 cups of water the thyme, basil, and garlic. Wait until it starts to boil and then drop the temperature to low. Partly cover with the pot's lid and simmer for about 40-45 minutes. At this point, most of the water should have evaporated from the pot. If not remove the lid and raise the temperature to medium and cook for a few minutes more. Until there is only a small amount of water left in the pot just enough to cover the bottom by ½ inch (1 cm) in height.
Take the pot off the heat and using an immersion blender blend the sauce until it looks very smooth.
Taste the sauce to check if it needs any additional seasoning. If the sauce is too runny because there was too much water left, you can cook it again uncovered over low heat until it reaches the consistency of your liking.
Let the sauce cool and transfer to a canning jar and store in the fridge for up to 6-7days.
You may also freeze the sauce in the canning jar just make sure to leave some space at the top about 1 inch (2-3 cm). You can keep the sauce in the freezer for up to 6 months. To unfreeze place the jar in the fridge overnight. And reheat the sauce the next day.