Awesome Portobello Brucetta...This should knock their socks off

"I thought 10 lbs of potatoes would be enough," is how Thanksgiving started last year at RJ and Melissa's house. I had never seen 10 lbs of mashed potatoes anywhere except at the Golden Corral, but it was the first Thanksgiving she was hosting and my first one away from home, so neither of us knew better.

This year, we've learned some lessons and Mel decided to throw another bash.  I've got some traditional Southern dishes I'm whipping up and more on that later, but the appetizer I'm contributing should knock their socks off.  Its one I found in a Gourmet a few years back and I made it for a bookclub meeting when we were reading The Other Boleyn Girl.  Here it goes:

Portobello Brucetta

1 1/2 cups balsamic vinegar
1/4 cup honey
1/4 cup (packed) golden brown sugar
1 1/2 tablespoons chopped fresh thyme
6 4-inch-diameter portobello mushrooms, stemmed, dark gills removed
3 tablespoons olive oil
3 red onions, sliced (about 6 cups)
2 large red bell peppers
3 tablespoons thinly sliced green onion
3 tablespoons chopped fresh basil
1 garlic clove, minced
1 3 1/2-inch-diameter sourdough or French-bread baguette, cut into 24 slices
Additional olive oil

Preheat oven to 375°F. Mix vinegar, honey, brown sugar and thyme in medium bowl. Transfer 1/2 cup marinade to small bowl; set aside. Place mushrooms in 15x10-inch glass baking dish. Pour remaining marinade over mushrooms. Cover baking dish with foil and bake until mushrooms are tender, about 40 minutes. Transfer mushrooms to work surface; cool. Cut mushrooms into 1/2-inch-wide slices.
Heat 2 tablespoons oil in heavy large skillet over medium heat. Add red onions and sauté until very tender and beginning to brown, about 25 minutes. Pour in reserved 1/2 cup marinade and cook until liquid is absorbed and onions are glazed, about 6 minutes. Set onions aside.

Char bell peppers over gas flame or in broiler until blackened on all sides. Enclose in paper bag and let stand 10 minutes. Peel, seed and chop peppers. Place peppers in medium bowl. Add green onion, basil, garlic and 1 tablespoon oil and toss to combine. (Mushrooms, onion mixture and bell pepper mixture can be prepared 1 day ahead. Cover separately and refrigerate.)

Preheat oven to 375°F. Place bread slices on baking sheet. Brush bread with additional olive oil. Bake until lightly toasted, about 10 minutes. Layer portobello mushroom slices, arugula, onions and then bell pepper mixture atop bread slices. Bake until heated through, about 3 minutes. Season to taste with salt and pepper.