I used the follow ingredients for the Whole30 Approved Dijon Mushrooms:
1/2 lb Mushrooms (I used Crimini)
Salt, pepper, and garlic powder–to taste
1 Tbsp Dijon Mustard
Saute the mushrooms with 1 Tbsp of oil over medium high heat until mostly browned. Add the salt, pepper, and garlic powder to taste. Add the Dijon mustard and heat through.