Place the tomatoes skin side down on a sheet pan lined with parchment paper and evenly spread on the garlic cloves. Next, drizzle the olive oil onto the tomatoes, season with salt and pepper and place on the thyme leaves. Bake in the oven for at least 2 hours but no more than 4 hours.
In a Le Creuset Pot on medium heat, add in the butter and caramelize the sweet onion. Add in the sugar to help brown.
Once the tomatoes are done cooking, add them in only to the roasted sweet onion pot along with 8 cooked cloves of garlic from the pan.
Next, add in the stock, balsamic vinegar, soy sauce, salt and pepper and simmer on low for at least 1 hour. Puree the soup in a blender or with an immersion hand blender.