Cut the beef to 2 or 3 big chunks, mix all ingredients and add required amount of water, enough to cover the meat.
Put in a pressure cooker with stopper, once the first whistle is released, lower flame and leave to cook for 20-30 mins, till tender.
Leave it to cool, open cooker and place back on gas and allow all the soup to dry up (roast).
Put off the gas and leave it to cool.
Then put it in a mixie and make a paste.
To make the sandwich paste: Add some butter (1/4 cup); tomato ketchup; mustard paste to the meat paste and mix well.
Add salt if needed.
The sandwich paste is ready for plastering on the bread.
Butter the slices (spread butter on both slices of the bread), put the meat sandwich paste on 1 slice of the buttered bread and cover it with the other buttered slice (only 1 slice should have the paste).