Rinse maesaengi in salt water, stirring with chopsticks to clean thoroughly.

Rinse maesaengi multiple times until no debris remains, then drain and cut into bite-sized pieces.

Rinse oysters in salt water, lightly rinse twice, and drain.

Cook spaghetti in boiling water with coarse salt for 1–2 minutes less than the package instructions.

Heat olive oil in a pan over low heat, add garlic and dried chili, and sauté until fragrant.

Transfer the cooked spaghetti to the pan and mix with the garlic and chili.

Add prepared maesaengi and oysters to the pan.

Add pasta water to help loosen maesaengi and stir-fry quickly.

Taste and adjust seasoning with fish sauce, salt, or oyster sauce. Add chopped green onion if available.