Tips: For a weeknight meal for 4, use 1/2 cup cider vinegar, 1 Tbsp. honey, 1/8 tsp. salt, 1 cup onion, 4 tortillas, 1/4 cup chutney, 8 oz. roast beef, and 4 cups arugula.
To make ahead: To pack for lunch: Wrap in plastic wrap and pack in an insulated bag with an ice pack.