Brush both sides of steak with olive oil.
Sprinkle with 1/4 teaspoon of salt and 1/4 teaspoon of pepper.
Place in shallow dish and pour Worcestershire over, rubbing to cover all the meat.
Cover and refrigerate for 2 hours, then grill.
In a large skillet melt butter over medium heat.
Add mushrooms, 1/4 teaspoon salt and 1/4 teaspoon pepper.
Cook for about 5 minutes until just tender.
Stir in half and half or cream.
Bring to boiling, immediately reduce heat.
Simmer uncovered for about 10 minutes or until slightly thickened.
Keep warm while grilling steak to desired degree of doneness.
Serve mushroom sauce with steak.
