Recipes Ingredients Meat & Poultry Beef Recipes Roast-Beef Sandwich 1.8 (9) 1 Review By Martha Stewart Editors Martha Stewart Editors Facebook Instagram Twitter Website An article attributed to "Martha Stewart Editors" indicates when several writers and editors have contributed to an article over the years. These collaborations allow us to provide you with the most accurate, up-to-date, and comprehensive information available.The Martha Stewart team aims to teach and inspire readers daily with tested-until-perfected recipes, creative DIY projects, and elevated home and entertaining ideas. They are experts in their fields who research, create, and test the best ways to help readers design the life they want. The joy is in the doing. Editorial Guidelines Updated on May 16, 2017 Print Share Share Tweet Pin Email Prep Time: 10 mins Total Time: 10 mins Servings: 1 Check our recipe for Roast Beef with Caramelized Shallots and use leftovers for this sandwich. Ingredients For the Sandwich 1 onion roll, halved ½ cup mixed greens 3 ounces thinly sliced leftover Roast Beef with Caramelized Shallots 2 thin slices red onion 2 cornichons, (or gherkins), halved lengthwise For the Spread 1 tablespoon reduced-fat mayonnaise 1 teaspoon prepared pesto 1 teaspoon grainy mustard Coarse salt and ground pepper Directions Make spread: Mix together mayonnaise, pesto, and mustard; season with salt and pepper. Layer bottom roll half with spread, greens, beef, onion, and cornichons; top with other roll half. Print