Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
1         Package       Portabella Mushroom Caps 
1/4       Cup           Olive Oil 
2         Tablespoons   Balsamic Vinegar 
1         Whole         Shallot -- finely chopped 
1         Clove         Garlic -- finely chopped

Preparation:

1. Remove stems and wipe caps clean with a damp paper towel. 2. Combine oil, vinegar, shallots and garlic. 3. Turn mushrooms on their backs, with dark "gill" side up. Spoon dressing over gills. 4. Grill on rack over hot coals, gill sides up, for 4 minutes. Slice and serve.