Place the chopped scallions and minced ginger in a heatproof bowl (ceramic, glass, or metal — never thin plastic). Add the salt and soy sauce (if using); stir.

Make sure the scallions and ginger are dry. Pat them down if needed. Wet aromatics make hot oil spit — do not use frozen scallions or ginger for this.

Heat the oil in a small saucepan over medium heat until hot but not smoking — roughly 350°F, when tiny bubbles form around a wooden chopstick dipped in the oil. Do not walk away from heating oil.

Safety pause: set the saucepan on a stable, heat-resistant surface. Keep your face and hands clear of the bowl. Pour the hot oil slowly and steadily over the aromatics — aim for the ginger. It will sizzle and bubble vigorously; this is expected. Do not pour all at once from a height.

Stir to combine. Let cool to room temperature, then transfer to a clean airtight jar.