Heat oil in a large wok or skillet over medium-high heat. Season oil with salt and add ginger and chile (if using a fresh chile, make sure to cut a slit in it to prevent it from bursting in the hot oil).
When ginger begins to sizzle, add spinach to skillet and toss, using tongs, to cook and evenly distribute flavor, until spinach is tender and wilted, 1 to 2 minutes. Serve warm or at room temperature.