Mario Batali's Roast Beef Po'Boy | Louisiana Kitchen & Culture

Ingredients

• 1 top round or chuck roast, 3 to 4 pounds
• Kosher salt and freshly ground black pepper
• 3 tablespoons extra-virgin olive oil
• 1 onion, thinly sliced
• 1/2 bunch thyme
• 1/4 cup all-purpose flour
• 1/2 cup water
• 6 (6-inch) lengths soft French bread, cut open and toasted
• Mayonnaise: 3 large tomatoes, thinly sliced
• Shredded iceberg lettuce
• Dill pickle chips