My friend got the recipe from Epicurious, as usual! I don't think they're very slim-line but they are delicious.
PORTOBELLO "STEAK" SANDWICHES WITH GORGONZOLA BUTTER AND RED PEPPER VIAGRETTE
For marinade
5 Tbsp balsemic vinegar
6 large cloves garlic, minced
2 Tbsp chopped fresh thyme leaves/2 tsp dried thyme
1/2 C olive oil
1 1/2 lbs fresh Portobello mushrooms, stems trimmed flush to cap
For Gorgonzola butter
2 oz (1/4 C) Gorgonzola cheese, at room temperature
1 Tbsp unsalted butter, softened
For red pepper vinaigrette
1 red bell pepper, roasted on direct fire and skin removed or 1/3 C bottled roasted red peppers, drained
1 Tbsp white wine vinegar
1 Tbsp water
2 Tbsp extra virgin olive oil
four 1/2 inch-thick slices of crusty bread
Make marinade:
Whisk together marinade ingredients, put half of mushroom caps and half of marinade in each of 2 large plastic bags (pressing out excess air), for 1-2 hrs Marinate at room temperature, turning over several times
Make Gorgonzola:
On a plate, mash Gorgonzola and butter together until blended welll
Make red pepper vinaigrette:
Blend vinaigrette ingredients with salt and pepper to taste until smooth and emulsified
Prepare grill.
Grill one side of bread until golden (approx. 1 minute). Spread Gorgonzola butter on soft side.
Grill mushrooms 2-3 mins on each side until tender. Slice thin.
Arrange warm mushrooms on toasts and spoon vinaigrette over each open-faced sandwich. Garnish with thyme (or not!)
