Step 1

Take pork loin out of the refrigerator and let it rest on the counter for 30-45 minutes to let it warm up before preparing it.

Step 2

Finely dice shallots and mushrooms and mince the garlic cloves.

Step 3

Preheat a large cooking pan over medium heat and add some oil. Add diced onion and cook until softened and starts to get golden brown.

Step 4

Add garlic and sauté just until fragrant.

Step 5

Add diced mushrooms, season with salt, pepper, and thyme and stir to mix. Let it cook until mushrooms are completely done and liquid release by the mushrooms is mostly cooked out.

Step 6

Transfer mushrooms into a mixing bowl and mix them with grated Gruyere cheese. Set the filling aside.

Step 7

Place pork loin on a large cutting board vertically, fat cap up.

Step 8

Using a long, sharp knife start cutting along the side of the meat, right where the fat cap ends, cutting in about 1/2 inch deep.

Step 9

Cut through a couple of inches of meat and then gently pull away the uncut part to kind of “unroll”.

Step 10

Keep cutting along and “unrolling” the meat, keeping the flat, cut part at about 1/2 inch thickness. Eventually, you will end up with a flat rectangle of pork.

Step 11

Some parts of the pork may be a little thicker, you can just even it out with a meat tenderizer. Cover the pork with a large piece of plastic wrap and then, use a flat side of the meat tenderizer to pound it. You’re not looking to make it thin, you just want to make the pork uniform thickness of about 1/2 inches throughout the rectangle.

Step 12

Preheat the oven to 350°F and line a roasting pan with aluminum foil to catch the drippings and make the clean-up easier.

Step 13

Season the inside of the pork with some salt and pepper.

Step 14

Spread Dijon mustard all over the top of the pork and spread the mushroom filling evenly as well. Make sure to leave about 1/2 inch at the top and the bottom without the filling.

Step 15

Starting at the left side (the end that was the inside of the pork loin), roll up the pork all the way.

Step 16

Use cooking twine to tie the loin all along the whole length in 1-inch intervals. Make sure not to tie too tight where it starts cutting into meat.

Step 17

Season the outside of the pork, on all four sides, with some garlic powder, salt, and pepper.

Step 18

Place tied pork loin onto the rack inside the roasting pan, fat cap up.

Step 19

Insert the probe of the leave-in meat thermometer through the side, toward the very center of the pork. (If you don't have a leave-in thermometer, you will need to take the pork out of the oven to take the temperature. Make sure to close the oven door each time you test to keep the heat in. Start testing after the first 45 minutes, and gauge from there, depending on the reading you get. Try not too test too often because poking holes in the meat will force the juices out.)

Step 20

Cook the pork in the oven until it reaches 140°F and take it out of the oven.

Step 21

Loosely tent it with foil and let it rest for about 10 minutes.

Step 22

Take the pork out of the pan and cut off the cooking twine. Tent the pork again loosely with the foil and let it rest for another 10 minutes.

Step 23

Have all the ingredients measured and ready on hand before starting to cook because this recipe will go fast. (If you have more that 1/4 cup of pork drippings, use everything you have and just add enough chicken stock to make 2 cups total liquid.)

Step 24

Melt butter in a cooking pan over medium heat. Once melted, whisk in flour until smooth and blended.

Step 25

While whisking, start pouring in the pan drippings, and chicken stock. Keep whisking until smooth. Add pepper and taste to see if you need to add any salt.

Step 26

Slowly stir as the gravy comes to simmer and thickens. Cook for a couple extra minutes, stirring slowly, and take off heat.

Step 27

Slice pork after it rested and serve right away with gravy on the side.