This is my adaptation of Portobello Mushrooms on Salad Greens (p. 190) from the Williams-Sonoma Complete Grilling Cookbook. I marinated two mushrooms in balsamic vinegar and olive oil with some dried basil and garlic powder (I'm lazy when it comes to garlic!). I then grilled them for about 4 minutes on a side. I served them sliced on a bed of baby spinach. The mustard vinaigrette contained spicy mustard, white vinegar, and olive oil. I would have used dijon mustard if I'd had it in the house. Fancy and healthy!