Using a 10" skillet, heat the butter and oil over medium-high heat until butter melts.
Add steaks. Saute until internal temperature reads 130º. This should only take no more than 3-minutes per side.
Make sure you under-cook the meat at this point.
DO NOT COOK IT TO SERVING TEMPERATURE.
Transfer meat to a plate and tent with foil.
Add mushrooms to skillet; saute until browned, 3-4 minutes.
Add garlic, basil and oregano; stir together and cook until garlic is fragrant, 40-60 seconds.
Combine the cream and vermouth in a cup.
Stir into skillet with mushrooms.
Turn down the heat to medium, and reduce mixture by half.
Add meat and accumulated juices to the pan.
Cook until meat reaches desired doneness.
Serve steaks with the sauce.
FOR THE POTATOES:After cooking potatoes till done - a fork enters the potatoes easily; drain in colander.
Return drained potatoes to hot pot; cover and cook for 1-2 minutes, removing any remaining moisture.
Remove from heat.
Stir in scallions, sour cream, butter and mustard.
Smash potatoes using a potato masher to reach desired consistency.
Season with salt and pepper.