How to Cook Bacon Wrapped Filet

As discussed, there are so many variables when cooking tenderloin steaks, such as the thickness of your steak, the heat of your skillet, your type of skillet, and your desired level of doneness – each will all impact the time it takes to cook your steak. To eliminate the guesswork and guarantee perfectly cooked, juicy steak every time, invest in an instant read meat thermometer. 
You can pick up an inexpensive instant read thermometer at the grocery store or Amazon, or I am obsessed with this digital probe thermometer – you will never overcook any protein again!  Instant read thermometers can be temperamental, but this digital probe thermometer retrieves temperature precisely to within ±1.8°f (±1°c ) and you leave it in the steak while it cooks, whether on the stove, grill or oven.
The digital thermometer allows you to set the desired temperature for each of the two probes and an alarm will set as soon as it reaches the set temperature – so walk away and be rewarded with perfectly cook filet mignon every time.

After the filets are cooked, immediately transfer them to a plate or cutting board so they don’t continue to cook.  As a rule of thumb, you want to let your steak rest for at least half of its total cooking time before slicing, so stick with 5-10 minutes to be safe.   
While the steak cooks, the juices are forced away from the heat to the middle of the meat.  The resting time allows for the redistribution and reabsorption of the juices throughout the whole steak for optimal flavor and juiciness.  If you don’t allow for this calming period, valuable juices will seep out and be lost when you slice into the filet, resulting in less juicy beef.

Cast iron is considered the gold standard for steak because:
It durable; can become screaming hot without warping
retains and distributes heat extremely well at a consistent temperature
seamlessly transfers from the stovetop to the hot oven
All of these factors combine to achieve a beautiful crispy, golden seared crust and a tender perfectly juicy interior. 
If you don’t own a cast iron skillet yet, you will not regret the purchase! Cast iron is a durable, chemical-free alternative to chemical-laden non-stick finishes. The more you use cast iron, the better it becomes, gradually developing a natural and slick patina (called seasoning), that makes it non-stick.   Cooking in a well-seasoned cast-iron skillet will also impart a bit of flavor, so if you have a cast iron skillet handed down to you, it is flavor gold!
If you don’t have a cast iron skillet, then a thick stainless steel or carbon steel pan are both good alternatives.   

Let the tenderloin steaks rest on the counter at room temperature for at least 60 minutes before cooking. The closer the steak is to your final temperature before cooking, the more quickly and evenly it will cook, otherwise, you can end up with cold spots or an overcooked exterior and cold interior.  This also gives the cold muscle fibers time to relax so they release natural moisture which is then reabsorbed into the muscle for juicier results (otherwise the moisture stays trapped in the fibers).

There is an in-depth scientific answer, but in short, season the steaks as soon as you remove them from the refrigerator, at least 40 minutes before cooking, up to overnight.  This allows time for the salt to penetrate through the surface of the meat and break down the muscle fibers so they can no longer contract when cooking, allowing the cells to hold onto more water resulting in juicier, more tender, flavorful steak. At first, you will see a glaze sitting on top of the filets as the salt extracts liquid, which then seeps back into the meat through osmosis.

Salt and pepper are musts for filet mignon.  You can also get away with more seasonings because filets are so mild in flavor. The kosher salt: 1) adds flavor (a steak can be seasoned with a plethora of seasonings and still taste bland without enough salt, 2) tenderizes the steak by helping to break down the proteins and muscle fibers in the meat so they can no longer contract, and 3) creates a golden crust by drawing out moisture resulting in a quicker Maillard reaction and crispier crust.  Pepper or another type of chili pepper is also crucial for flavoring. Add other desired seasonings in quantities that still let the natural flavor of the steak shine.

Use a neutral, high smoking point oil for both pan searing and grilling steak such as vegetable oil, canola oil or grapeseed oil.   Other oils (including olive oil) have a lower smoking point, around 400 degrees F, which means that overheating will not only smoke you out but can adversely impact its flavor and ruin the flavor of your steak. Most importantly, it can produce low levels of harmful compounds.

First, the steak needs to be dry otherwise the moisture will steam your steak.  Next, get your pan hot, hot hot!  Once you add the steak to the hot grill or pan, resist the urge to touch the steak before 2 minutes.  The steak needs constant direct heat to develop the intensely flavored, signature crust.  If you keep moving or rotating the steak, it will brown but won’t char.