You can grill the eggplant and arrange on the platter up to 4 hours in advance. Drizzle with dressing and garnish with herbs and feta right before serving.
1/2 cup extra-virgin olive oil
5 garlic cloves, chopped coarse
1/4 tsp. red pepper flakes
3 lemons, halved crosswise
Salt and pepper
2 large eggplants (about 3 lb.), sliced into 1/2"-thick rounds
4 oz. feta cheese, crumbled (1 cup)
4 scallions, thinly sliced
1/2 cup chopped fresh mint leaves
1/2 cup roasted and salted pistachios, chopped coarse