3 medium sweet onions, such as Vidalia or Maui
2 T olive oil, plus extra for brushing
1 tsp. mustard seed
1 tsp. celery seed
1 tsp. cracked black pepper
4 C beef stock
1/4 C red wine
1 T Worcestershire sauce
1 large portobella mushroom
3 slices Gruyere or provolone cheese
salt and pepper
Serves 4
Recipe
Slice the onions very thinly. Place a 5-quart stockpot over medium-high heat. Add the olive oil and the onions.
After about 10 minutes, lower heat to medium low. Add salt and pepper to taste, mustard seed, celery seed, and cracked pepper and continue to saute the onions until carmelized to a deep golden brown, another 20-25 minutes.
When the onions are a rich brown, add the beef stock, wine and Worcestershire sauce. Turn the heat up to medium and cook for about 15 minutes. Preheat the broiler.
In the meantime, cut the stem off the portobella mushroom. Place the mushroom on its side and slice into 4 thin pieces. Heat a large skillet over medium high heat. Brush mushroom slices with olive oil and place in skillet, cooking for a couple of minutes on each side until lightly browned.
Ladle the soup into 4 oven safe bowls. Place a mushroom slice on top and a slice of cheese. Place bowls on a cookie sheet and place under the broiler until cheese gets brown and bubbly.
**Note from Suzanne: This soup is best when served in stoneware or other oven safe bowls, because you can then place the bowls on a cookie sheet under the broiler for a minute or two and let the cheese get brown and bubbly.