Peel the potatoes and cut them in to 4 pieces. Bring the water into boil and add little salt, then cook the potatoes for about 5 minutes.
While potatoes are cooking, chop the onion, green chili, garlic, ginger and curry leaves very finely.
Check the potatoes is cooked, you can pierce it with a fork, if cooked, it'll easily go through. Take it off the boiling water and transfer it to a bowl or another container and mash them. Make sure to add salt and pepper to your taste while mashing.
Heat up a pan and add olive oil. Saute chopped onion,ginger,garlic,green chili,curry leaves, cumin and mustard for about 2 minutes.
Mix the canned fish (tuna) with mashed potatoes and add salt and pepper to taste. Then mix with the spices on the pan for about 1 minute.
Apply the paste on the biscuits (cream cracked) and close it with another biscuit like a sandwich.
Beat 3 large eggs on a bowl. Dip the biscuit (sandwich) in the beaten eggs and apply bread crumbs all over it.
Heat up a pan and add vegetable oil. Deep fry the biscuit about 10 second each side and take it out.
Wait a little while its to cool down and enjoy while its hot (worm).