Ingredients:

• 1 3/4 to 2 pound section beef tenderloin (preferably a piece cut from the center), trimmed of excess fat and silverskin
• 1 teaspoon kosher salt
• 1/2 teaspoon coarsely ground black pepper
• 1 1/2 tablespoons extra virgin olive oil
• 1 pound cremini mushrooms, sliced 1/8 to 1/4 inch thick
• 3 tablespoons butter
• 1 teaspoon salt (use 1/2 teaspoon if using salted butter)
• 2 tablespoons minced shallots
• 2 tablespoons minced garlic
• 1 1/2 teaspoons herbs de Provence or 1 teaspoon of dried tarragon