Saute the onion and carrot in the oil until slightly softened, but not browned. Add the tomatoes and their juice, tomato puree, bones and sachet. Bring to a boil and reduce heat, simmering over very low heat for 1½ to 2 hours, until reduced to desired consistency.
Remove sachet and bones. Strain sauce, or pass through a food mill. Adjust seasoning with salt and sugar.