Cube the beef and slice the mushrooms. 1 hour before cooking, LIBERALLY salt and pepper the tenderloin tips. Toss to coat well. Set aside to come to room temperature.
In a large skillet, cast iron skillet, or enameled braiser, heat the olive oil over medium-high heat until shimmering. Add the beef all at once and spread to one even layer. Resist the urge to move the beef tips around the skillet instead, allowing the layer to brown on one side. Tips are ready to be turned when they freely release from the pan when nudged.
Brown nicely on all sides but avoid cooking the beef through completely. Use a slotted spoon to remove beef tips to a bowl to keep warm. Set aside.
Reduce heat to medium and add the mushroom slices in a single layer. Again, resist the urge to move around the pan instead allowing them to begin to brown and turn a lovely golden color, about 4 to 5 minutes. Use the slotted spoon to remove the mushrooms to the platter with the meat.
Return the hot skillet to low heat and add the butter. Once melted, add the shallots. Cook, stirring frequently, about 2 minutes. Add the garlic and cook 1 minute more. Now spoon in both mustards and the beef broth and stir, bringing to a boil. NOTE ** If feasible, I encourage adding any accumulated beef juices to the pan before bringing it to a boil. Stir, scraping up any browned bits stuck to the bottom.
Add the wine and Worcestershire sauce and continue boiling. Continue to cook and stir until the sauce is slightly reduced, about 5 minutes.
Remove the pan from the heat momentarily to add the cream. Whisk to incorporate. Return to the heat and simmer very low until the sauce is slightly thickened and coats the back of a spoon, about 5 minutes. Turn off the heat and stir in half each of the freshly chopped parsley, thyme, and sage. Taste for seasoning and add salt or pepper if necessary.
Return the beef and the mushrooms to the skillet and stir to combine with the herbed pan sauce. Simmer for about 10 minutes or until steak tips are medium-rare to medium, and register about 130°F.
Garnish with the remaining halves of chopped fresh parsley, thyme, and sage. Serve tips spooned over a comforting starch.