In a medium skillet, heat two tablespoons of olive oil.
In a skillet, cook thinly sliced onions until they become soft and golden brown, about 20-25 minutes.
To deglaze and intensify the flavor of the onions, you can add a splash of water or balsamic vinegar.
Crisp and lightly golden baguette or sourdough slices can be toasted in the oven.
Place the toasted slices on a serving platter or individual plates.
Spread a generous layer of horseradish cream over each slice of bread.
Thinly slice the roasted beef against the grain and arrange the slices over the horseradish cream.
Top the beef with a handful of fresh arugula, followed by a spoonful of caramelized onions.
Over each sandwich, place a slice of provolone, Swiss, or blue cheese.
Add a sweet and sour glaze to the sandwiches by drizzling a balsamic sauce over the top. This enhances both the flavor and presentation.
The wonderful fusion of tastes and textures that make the Yummy Roast Beef Open Faced Sandwich such a treat should be served right away.
Enjoy your delicious creation!