I'm a strict vegetarian and am looking for some baked portobello mushroom ideas.

I'm currently marinating 2 portobello caps + stems in mirin, soy sauce and garlic to bake for tomorrow's dinner, and will be adding the leftover marinade to cornstarch to thicken and top an Asian-influenced mushroom sandwich recipe.

Any suggestions (cheaper ones, since I'm a college student, and baked, since my smoke detector goes nuts when I pan fry) greatly appreciated!

Thanks!