Portobello-Eggplant Burger with Smoked Mozzarella and Tapenade

This is not a burger in the sense that nothing is ground up and shaped into a patty, but this combo has a kind of burgerness about it. The meaty portobello enhanced by the smokiness of the mozzarella gives this vegetarian burger a hearty, almost carnivorous edge. You need a sturdy bun for this burger, like a semolina roll or some crusty French bread.

MAKES 4 BURGERS

• ¹/₂ cup kalamata olives, pitted
• 2 anchovy fillets
• 1 teaspoon Dijon mustard
• 4 tablespoons olive oil
• Four ¹/₂-inch-thick slices medium onion
• Four ¹/₂-inch-thick slices peeled eggplant
• 4 portobello mushrooms, about 4 inches across, stemmed
• Four ¹/₄-inch-thick slices smoked mozzarella (see note)
• 4 semolina rolls or 4-inch lengths of crusty baguette
• Four ¹/₂-inch-thick slices tomato

Combine the olives, anchovies, and mustard in a blender and process until just smooth. Set aside. (The tapenade will keep, covered and refrigerated, for up to 2 days.)

Place a skillet, preferably cast-iron, over medium-high heat and let it get hot, about 1 minute. Add 1 tablespoon of the olive oil and spread it evenly over the pan. Add the onion slices and cook 4 minutes, until lightly browned on the first side. Turn, taking care to keep the slices intact, and cook 4 minutes more to brown the second side. Transfer the onion slices to a platter and lay a piece of foil over them to keep them warm.

Add 1 more tablespoon of the olive oil and spread it evenly over the pan. Add the eggplant slices and cook 4 minutes, until they are lightly browned on the first side. Turn and cook 4 minutes more until softened and browned on the second side. Transfer the eggplant slices to the platter with the onions and re-cover to keep warm.

Add the remaining 2 tablespoons of the olive oil and spread it evenly over the pan. Add the mushrooms, top-side down, and cook 4 minutes, until they are lightly browned. Turn and place cheese slices on top of the mushrooms. Cook 4 minutes more. Transfer each mushroom to one of the rolls.

Add the tomato slices to the pan and cook for 15 seconds. Turn and cook 15 seconds more. Remove and set aside.

Arrange an eggplant slice over the melted cheese on each of the mushrooms. Place an onion slice on the eggplant. Finish with a slice of tomato and serve topped with 2 tablespoons of the tapenade.

For charcoal-grilled burgers, make a medium fire (see note, page 12). Make sure the grate is clean and oiled. Brush the mushrooms, eggplant, and onion slices with oil and grill them all at the same time for 4 minutes. Turn and cook 4 to 5 minutes more. Place the slices of cheese on the mushrooms after turning. Serve the tomatoes on the sandwiches without grilling.

For gas-grilled burgers, preheat on medium-high until the grill is hot. Make sure the grate is clean and oiled. Brush the mushrooms, eggplant, and onion slices with oil and grill for 4 minutes with the cover closed. Turn and place the slices of cheese on the mushrooms. Cook 4 to 5 minutes more, cover closed. Serve the tomatoes on the sandwiches without grilling.

Note: Smoked mozzarella is available in Italian markets and many specialty food shops. If you can’t find it, substitute smoked Cheddar. If you want to forgo the smoked cheese altogether, substitute plain mozzarella, Gorgonzola, Gruyère, or your favorite hard or semi-hard cheese.