Ginger Shiitake Beef Tenderloin

Preheat your oven to the desired temperature of 400 degrees Fahrenheit (200 degrees Celsius).

Next, heat a generous amount of olive oil in an oversized oven-safe skillet over extremely high heat until it starts to emit a light smoke. Prepare the filets according to your personal taste preferences by sprinkling them with salt and pepper. Cook the filets in the skillet for approximately 3 minutes on each side, or until they achieve a golden brown color.

Transfer the cooked filets to the preheated oven and continue cooking them until they reach your desired level of doneness, approximately 12 minutes for medium-rare.

While the filets are cooking, melt a substantial amount of butter in a saucepan over medium-high heat. Introduce the ginger and garlic into the saucepan and cook until they become translucent and fragrant, but avoid letting them turn brown, approximately 1 1/2 minutes.

Add the shiitake mushrooms to the saucepan and cook them for 3 to 4 minutes, or until they become soft.

Pour in the sake and mirin into the saucepan and simmer the mixture until it has reduced by half.

Melt the remaining 3/4 cup of butter, then decrease the heat to a lower setting and cook until the butter turns a rich brown color, approximately 6 to 8 minutes.

Once the butter has reached its desired color, season it with salt and pepper to taste, then stir in the chives.

Spoon the prepared sauce over the cooked filets to serve.