Sprinkle both sides of the eggplant with salt and spread in a colander. Rest 20 to 30 minutes. Rinse thoroughly under cold water, then press or squeeze completely dry with paper towels.
Add all whipped feta ingredients to a blender or small food processor. Process 30 to 60 seconds until completely smooth and creamy.
Whisk together the olive oil, grated garlic, red pepper flakes, and black pepper. Brush both sides of the eggplant generously. Heat the grill to medium-high, clean the grates, then oil them just before cooking.
Place the eggplant on the grill and do not touch for 4 to 5 minutes. Flip when it releases cleanly. Grill the second side 4 to 5 minutes, until a knife pokes through with zero resistance.
Spread the whipped feta across a platter. Arrange the grilled eggplant over the top. Drizzle with olive oil and scatter with torn mint and toasted pine nuts.
Video
Notes
Salt-curing: Do not skip the salt cure. It collapses the air pockets so the eggplant chars instead of soaking up oil.Make ahead: The whipped feta keeps up to 3 days chilled. Store grilled eggplant up to 4 days in the fridge.