Place filets in a single layer in a glass dish.
Mix olive oil, salt, pepper, soy sauce, sugar and mustard in a small bowl.
Pour marinade over filets, ensuring all four are evenly coated. Cover and set aside for about 10 minutes.
Preheat STOK Grill with Wok or Griddle Insert to medium heat, between 300°F -350°F
If using the STOK® Tower, click here for heating tips.
Once grill is heated, transfer the filets to the Wok OR Griddle. Place them skin-side down. Close lid and let cook for about 4-5 minutes, until light pink and can be pierced with a fork. Carefully remove the filets with a spatula.
Serve.
