Peel and devein shrimp. Sprinkle with lemon juice and set aside.
Melt butter in large skillet. Saute garlic, green onion tops and tomato wedges. Add shrimp and season with oregano, salt and pepper to taste. Turn shrimp frequently and saute until pink. Add feta cheese and cream sherry. Bring to boil and cook 3 to 4 minutes. Remove shrimp carefully to casserole. Spoon cheese-sherry mixture over shrimp.