Presumably many of these varieties could be substituted if necessary, though research into the actual varietal soil contents near Platina's home would probably be most telling in attempting a comparison to modern sweet onions. If similar soil types could be found where one of the sweet American varieties is grown, that substitution would seem to be the best choice given the possibly inaccessible original. Instead, we chose to save time and make use of an abundance of ovens at the feast site. For this reason, the instructions for making this dish suggest chopping and then alternately steaming and roasting the onions to cook them. If you wish to cook the onions whole, we suggest planning extra time into the cooking schedule.
Baked onions hold heat for a very long time.
You will need the extra time in your schedule to wait for the onions to cool to a level safe for handling. You can speed this process by peeling the onions prior to baking them. Your tears are the result of an onion's attempt to protect itself. Chopping releases gasses from the onion's flesh which, when combined with human tears, results in the formation of sulfuric acid. However, all hope is not lost.