Steps
1. Season the beef with salt and pepper. Grill or pan-fry it over medium heat until cooked to your liking (about 5-7 minutes for medium-rare).
2. While the beef is cooking, slice the avocado and set aside.
3. Once the beef is done, let it rest for a minute before slicing it thinly.
4. Assemble the sandwich: layer one slice of bread with cheese, followed by the sliced beef and avocado. Top with another slice of cheese and the second slice of bread.
5. In a small pan, melt the chocolate with the sugar over low heat until smooth.
6. Drizzle the melted chocolate over the finished sandwich before serving.