Soba only exists as a .png file in Pam's+HarvestCraft+1.12.2zc+The+7mm+Kidney+Stone+Update.jar\assets\harvestcraft\recipes. There are no other files relating to this item in the modpack (such as the recipe).

Please note I mis-reported the item as "Soba". The item would in fact be "Soba Noodles". The known file is properly labled as such (sobanoodlesitem.png).