Not Mustard, Not Au Jus: Roast Beef Sandwiches Are 3X Fancier When You Spread This Jarred Condiment

A roast beef sandwich certainly doesn't have to be boring. Whether you're cooking the meat in French onion soup or braising the beef with beer and garlic, there are plenty of ways to pack this classic sandwich with flavor. Though typical presentations serve the sandwich with a cup of au jus or a side of mustard, offering it with a side of caramelized onion jam upgrades the meal with restaurant-worthy appeal.

Made by slowly cooking onions with sugar and vinegar, even an easy onion jam recipe can add a sweet and savory element that mustard can't compete with — plus you can customize the flavor profile with more or less sugar, black pepper, and herbs like rosemary and thyme. The jam's sweetness balances the beef's saltiness, and while au jus is soaked up immediately by bread, spreadable jam sits on the surface, keeping the outside of the bread crisp and firm. It can be slathered directly onto the top slice of a bun or roll, allowing it to meld with the warm beef. This kind of flavor-packed sandwich has some fans dreaming about eating it for breakfast.

To add another layer of flavor, toast the bread or brush it with garlic butter before adding the jammy topping. Melted mozzarella, provolone, goat cheese, and Swiss would also all pair beautifully with the jam — just remember to make more than you think you'll need, as it can be served with other comfort foods, like grilled veggies, baked potatoes, barbecued proteins, toasted pitas, and mac and cheese.

You can also dress up roast beef sandwiches with your own special touches. An extra crumble of blue cheese, a smear of zesty horseradish cream, or a heap of quick-pickled red onions can turn a run-of-the-mill recipe into a gourmet experience. "This was the best sandwich I've ever had," wrote one user on Instagram about a creation made with toasted sourdough, onion and garlic jam, sliced roast beef, caramelized onions and mushrooms, cheddar, arugula, and a balsamic drizzle. Serve your creation with crispy fries or a bowl of your favorite soup for the ultimate comfort meal.