Slice the green onion diagonally into 1cm pieces, shred the shiso leaves, and thinly slice the garlic. Drain the saba can.

Boil water in a pot, add salt (not listed in ingredients) and spaghetti. Cook 1 minute less than the package instructions, then drain.

Heat olive oil in a frying pan over medium-low heat. Add garlic and chili flakes, cooking until fragrant. Add green onion and cook until browned.

Add the drained saba can and stir-fry until the liquid evaporates. Mix in soy sauce and combine with the spaghetti.