Prep: 1. Thinly slice the garlic. Make: 1. Heat oil over medium heat. 2. Add garlic; cook, stirring, until fragrant but not browned, 2 to 3 minutes. 3. Add arugula; cook until slightly wilted, 1 to 2 minutes. 4. Add vinegar; cook, stirring, until most of the vinegar has evaporated, about 1 minute. 5. Season to taste with salt and pepper; serve immediately.
The vinegar is optional if you prefer to leave it out.