Heat the olive oil in a large non-reactive pot over moderate heat. Add the garlic and saute until caramelized, about 5 minutes. Add the tomatoes to the garlic and bring to a simmer. Add the parsley and basil and simmer until reduced to a sauce-like consistency, about 15 minutes.
Taste and adjust the seasoning. If the sauce tastes too acidic, add the baking soda and cook for 5 more minutes. If it needs a touch of sweetness, add the sugar and cook for 5 more minutes. Remove the basil stem before serving.