Portobello Burgers With Green Olive Tapenade

Portobello Burgers With Green Olive Tapenade are funky and slightly off the beaten veggie burger path with a briny sauce that will send your taste buds into cartwheels of happiness.  All modesty aside, we are were feeling pretty chuffed with ourselves when we first bit into these burgers, creamy mozarella melts into smokey portobellos with a full meaty texture.  Green olive tapenade brings a mysterious licorice and sea salty flavor, respectfully sandwiched between rolls liberally smeared by basil mayonnaise. High-fives and groans of delight were followed by a respectful 5 minutes of silent appreciation (read: scarfing) of these Portobello Burgers With Green Olive Tapenade.

Tapenade is from the Provence region of France and is traditionally made with black olive and anchovies, having neither on hand, but a hankering for a snappy dip, this was our own concoction. We played with the combination of parsley, tarragon, capers and green olives until we reached a good balance of briny versus herbacious. The grilled portobello marinade and mushroom preparation was adapted from Cooks Illustrated.


Yield: 4 Portobello burgers with toppings. 1 1/4 cups tapenade.


   Burgers & Toppings:

  • 4 Large portobello mushrooms, washed
  • Fresh mozzarella or aged cheddar, cut into 1/2 inch slices
  • 1 beefsteak tomato, cut into 1/2 inch slices
  • Fresh basil leaves or fresh lettuce, washed
  • Half red onion, cut into 1/2 inch slices
  • 4 hamburger rolls, split in half, lightly toasted or grilled

Portobello Marinade:

  • 1/2 cup canola oil
  • 3 tablespoons red wine vinegar
  • 2 garlic cloves, crushed
  • 1 teaspoon salt
  • 1/2 teaspoon pepper

Basil Mayonnaise:

  • 1/2 cup chopped fresh basil
  • 1/2 cup mayonnaise
  • 1 garlic clove, crushed
  • 1 teaspoon fresh lemon juice

Green Olive Tapenade:

  • 1 1/4 cups Spanish green olives
  • 3 tablespoons olive oil (preferably extra virgin)
  • 1 tablespoon capers
  • 2 stalks green onions, roughly chopped
  • 2 tablespoons fresh tarragon, roughly chopped
  • 2 tablespoons fresh parsley, roughly chopped
  • 1/2 teaspoon kosher salt
  • 1/4 teaspoon ground black pepper
  • 1 tablespoon white wine vinegar (can substitute red wine, cider)
  • 3 garlic cloves, crushed


  1. To prepare the tapenade, put all ingredients (olives, oil, capers, green onions, tarragon, parsley, salt, pepper, vinegar, garlic) into food processor, blender or mortar and puree until mixture has come together in a fairly uniform paste.  Adjust salt and pepper to taste.  Refrigerate, sealed tightly for up to 1 week.
  2.  To prepare the mushrooms, remove the stems and with a spoon and scrape out the gills (underside) of the mushrooms.  Flip the mushroom over and using a sharp knife, make a shallow tic-tac-toe pattern on the top of each of the caps. This will promote a more tender texture and allow the marinade to permeate deeper into the mushroom. 

  3. Mix together the marinade ingredients; oil, vinegar, garlic, salt and pepper in a large zip top bag and add the prepared mushrooms.  Seal the bag and allow the mushrooms to marinate for at least 30 minutes, we would not recommend longer than 1 hour.
  4. Preheat your grill, covered, at high heat for 15 minutes.
  5.  In a separate bowl, whisk together basil mayonnaise ingredients (mayonnaise, basil, lemon and garlic).  Set aside.
  6. Clean and oil the grill.  Remove mushrooms from the marinade and drop your onions into the marinade to coat them briefly with the oil mixture.  Place the mushrooms and onions on the grill.  The mushrooms should be placed top side down.  Cover the grill and cook until mushrooms have nice grill marks (4-6 minutes).  Flip mushrooms and onions over and grill covered until the mushrooms have grill marks on the other side (3-5 min).
  7. Remove mushrooms and onions, and cover while you briefly grill the buns. If your grill is large enough you can do this as your mushrooms are finishing.
  8. To serve, spread basil mayonnaise on bottom bun, top with tomato, lettuce, mushroom, grilled onion, and mozzarella. Spread your top bun with tapenade. Enjoy!