- Reserved cooking liquid from Braised Beef Tacos
- 2 tablespoons canola oil
- 1 medium onion, sliced
- 4 tablespoons unsalted butter, softened
- 1 small loaf French bread, sliced on the bias into 8 slices
- Reserved 1 1/2 cups shredded beef from Braised Beef Tacos
- Reserved 1/2 cups Monterey Jack cheese from Spicy Fajita Soup
In a small pot over medium heat, add the reserved cooking liquid and cook until it is hot.
Butter 1 side of each slice of bread. Layer the beef, onions, and cheese evenly over the plain side of 4 bread slices. Top each with the other 4 slices of bread, buttered-side up.
Heat a grill pan over medium-high heat and grill the sandwiches until golden brown on both sides and the cheese is melted, 4 to 5 minutes per side.
Serve the sandwiches with the hot beef jus for dipping.