Roasted Eggplant & Garlic Mayo:
1 large eggplant (1 1/2 pounds), sliced into 1/2"-thick rounds
1/4 cup olive oil
1/4 teaspoon smoked paprika
Kosher salt, ground pepper
Freshly ground black pepper
1 garlic clove, finely grated
1/2 cup mayonnaise
2 teaspoons Sherry vinegar
Beet Salad & Assembly:
4 scallions, thinly sliced
1 cup mixed tender fresh herb leaves (such as flat-leaf parsley, dill, and mint), torn if large
1/2 cup chopped pickled beets
1/4 cup chopped pitted oil-cured olives
2 tablespoons drained capers
1 tablespoon olive oil
4 6x4" pieces focaccia, split
6 ounces feta, thinly sliced or crumbled
For Roasted Eggplant & Garlic Mayo:
Preheat oven to 400°F. Place eggplant slices on a large rimmed baking sheet and rub both sides with oil. Season with paprika, salt, and pepper. Roast until golden and tender, 30-40 minutes.
Whisk garlic, mayonnaise, and vinegar in a small bowl; set aside.
For Beet Salad & Assembly:
Toss scallions, herbs, beets, olives, capers, and oil in a medium bowl to combine.
Spread cut sides of focaccia with garlic mayo. Build sandwiches with focaccia, eggplant, feta, and beet salad.
DO AHEAD: Eggplant can be roasted 1 day ahead. Cover and chill.