Preheat a grill or grill pan to medium-high. Using a food processor, puree 1/4 cup water, the shallot, almonds, parsley, sun-dried tomatoes, vinegar, Worcestershire sauce and mustard. With the machine on, pour in 1/2 cup EVOO to form a smooth, thick dressing. Pour about two-thirds of the dressing into a large bowl. Add the mushroom caps and turn to coat.