Slice the beef tenderloin into thin strips.
Season with salt and pepper.
In a skillet over medium heat, melt 1 tablespoon of butter.
Add olive oil and beef strips.
Cook until browned, and then set aside.
In the same skillet, melt the remaining butter.
Add flour, whisking until smooth.
Gradually pour in beef consommé, stirring continuously.
Stir in Dijon mustard, followed by sour cream.
Mix well and simmer until thickened.
Return the beef to the skillet.
Cook for a few more minutes until heated through.