Heat the olive oil in a large skillet over medium high heat. Add the bacon and cook until golden and beginning to crisp, about 5 minutes. Add the beef and cook until just browned, about 3 to 4 minutes. The cubes should be very rare in the center. Transfer the meat and bacon to a bowl.
Turn off the heat and pour in the cognac. Add the vegetables. Turn on the heat and simmer until most of the liquid disappears. Pour in the wine and simmer until most of the liquid disappears. Pour in 1 cup beef broth. Reduce until most of the liquid disappears. Pour in the last cup of broth, and reduce until there is about 1 cup liquid remaining in the skillet with the vegetables. This process will take about 10 minutes.
Add the meat back into the sauce, season with salt and pepper. Stir in the cornstarch slurry. Cook until the sauce is smooth and shiny, about 2 minutes. The meat should remain rare to medium-rare. Sprinkle fresh parsley over top.