Heat oil in a large skillet over medium heat.
Add garlic; cook, stirring constantly, until garlic is fragrant but not browned, 2 to 3 minutes.
Add arugula; cook, stirring constantly, until slightly wilted, 1 to 2 minutes.
Add vinegar; cook, stirring constantly, until most of the vinegar has evaporated, about 1 minute.
Stir in salt; season with pepper.
Serve immediately.
