So I cooked this herbal egg as below for him to bring to school.
First, buy the egg and wash the egg with sponge to make sure the egg shell is clean. Buy the herbal egg spices 1 packet from any Chinese drug shop or Supermarket. This herbal egg spices come with two packet of the spices in tea bag type. if you cook 30 eggs put in 1 packet of the spices will do . if you cooked more than 30 eggs then you may need to put in 2 packet of the spices.
After wash the egg, cooked the egg as hard boiled egg and use spoon to crack the egg shell.
After all the hard boiled egg were cracked then put all the egg into the big pot and add water till cover the eggs and put in the herbal egg spices, 200ml light soya sauce, 200g sugar, 1tbsp dark soya sauce (if you want darker colour you may add 2 to 3 tbsp dark soya sauce.), 1 tsp salt to boil it. After boiled then turn it to slower fire continue boil for 2 to 3 hours. (if you cook 20-30 eggs, ideally boiled it in slower cooker and let it cooked over night this will make the egg taste fantastic.)
the look after a few hour cooked.