I dont think oil in Chinese food is connected to numbness
in arm, as the oils in the food are digested by the enzymes in stomach, causing oil to disintegrate.
There might be another reason of the numbness of your hand, it might be due to some nerve
weakness as you are vegan and vegans have reduced levels of certain vitamins
in blood !! So you are advised to eat some vitamin supplements.
hope my info helped you
Dr Hari Om Chandrakar