Blue Cheese-Topped Mushroom Steaks over Arugula
1. Brush grill grates with oil, and preheat grill to medium.
2. Whisk together olive oil and vinegar in bowl. Season with salt and pepper, if desired, and brush all over mushroom caps. Place caps on grill, and cook 15 to 18 minutes, turning once, or until tender. Transfer to cutting board to cool slightly before slicing.
3. Process garlic in food processor until minced. Add buttermilk, blue cheese, and mayonnaise; process until creamy. Stir in chives.
4. Divide arugula among plates. Top with portobellos, tomatoes, and sauce.