Boil the pasta. Crush the plum and place it in a bowl with the tuna. (You don't need to drain the oil out of the can, just use the tuna in as-is).
Drain the boiled pasta and add to the bowl. Mix well. Add a splash of soy sauce.
Done! Add some black pepper to taste!
Story Behind this Recipe
This is a pasta dish I used to make a long time ago.
Since you're using the oil from the tuna can, the noodles won't stick together even if they sit for a while. If you're not a fan of the oil from canned tuna or if you are using boiled tuna, add a bit of olive oil instead. I used soft umeboshi.