This recipe was originally an appetizer I offered in a downtown Boston bistro, but when I saw the mass appeal for it, I quickly remade it as a main dish. It remains one of my most popular sandwich dishes to this day. It is surprisingly simple and quick to make.
Step: 1
Stir beef, Worcestershire sauce, and Montreal steak seasoning together in a bowl. Marinate beef while preparing other items.
Step: 2
Heat olive oil in skillet over high heat. Cook and stir onions in hot oil until golden brown, about 15 minutes; add balsamic vinegar, salt, and black pepper. Reduce heat to low and cook the onion mixture at a simmer until there is little liquid remaining and the mixture is syrup-like in texture, about 10 minutes.
Step: 3
Preheat an outdoor grill to 400 degrees F (200 degrees C) and lightly oil the grate.
Step: 4
Remove steak pieces from the marinade and shake off excess. Discard the remaining marinade. Combine beef and canola oil in a bowl and toss to coat.
Step: 5
Preheat oven to 200 degrees F (95 degrees C).
Step: 6
Cook the beef slices on the hot grill, turning frequently, until they start to firm and are reddish-pink and juicy in the center, 4 to 6 minutes per side. An instant-read thermometer inserted into the center should read 130 degrees F (54 degrees C).
Step: 7
Arrange rolls onto a baking sheet. Spoon onions into the bottom of the sandwich rolls; add beef. Top beef with Brie cheese.
Step: 8
Heat in preheated oven until the cheese melts, about 5 minutes.
Per Serving: 575 calories; protein 35.9g; carbohydrates 45.7g; fat 26.7g; cholesterol 99.5mg; sodium 1380.1mg.