Portobello Eggplant Burgers with Grilled Onions, Blue Cheese and Arugula

Serves 4

1/2 globe eggplant, cut into 1/2-inch thick slices
1 red onion, cut through the root end into 8 wedges
Olive oil for brushing
Kosher salt
Freshly ground black pepper
4 portobello mushrooms, stems trimmed
4 crusty rolls, split horizontally
4 ounces blue cheese, crumbled
2 cups loosely packed baby arugula leaves
Good quality balsamic vinegar

Brush the cut sides of the eggplant and onion with olive oil and sprinkle with salt and pepper. Brush the tops of the mushrooms with olive oil and sprinkle with salt and pepper. Turn the mushrooms gill-side up and sprinkle again with salt and pepper.

Prepare a grill to medium hot (you can hold your hand at grate level for 3 seconds). Cook the eggplant and onion 7 to 8 minutes, turning halfway through, until tender and slightly charred. Cook the mushrooms gill-side up 5 to 7 minutes, until softened and juicy-looking. Grill the cut sides of the rolls for 30 to 60 seconds, until lightly toasted.

Set a mushroom on the bottom half of each roll. Top with eggplant, onions, blue cheese and arugula, dividing evenly. Drizzle each with a little balsamic vinegar. Add the top halves of the rolls and serve.