1
Preheat grill to medium-high.
2
Mash garlic into a paste on a cutting board with the back of a spoon.
3
Combine with mayonnaise and lemon juice in a small bowl.
4
Set aside.
5
Coat both sides of eggplant rounds and mushroom caps with cooking spray and season with salt and pepper.
6
Grill the vegetables, turning once, until tender and browned on both sides: 2 to 3 minutes per side for eggplant, 3 to 4 minutes for mushrooms.
7
When cool enough to handle, slice the mushrooms.
8
Spread 1 1/2 teaspoons of the garlic mayonnaise on each piece of bread.
9
Layer the eggplant, mushrooms, arugula (or spinach) and tomato slices onto 4 slices of bread and top with the remaining bread.
Tips & Notes
The dark gills found on the underside of a portobello mushroom cap are edible, but can turn a dish an unappealing gray/black color. Gently scrape the gills off with a spoon.
