Preheat grill to medium-high heat.

Slice eggplants into ½” slices. In a small dish, combine 3 Tbsp of olive oil with thyme, salt and pepper. Brush each slice of eggplant with this olive oil mixture.

Using aluminum foil, create a foil pouch and add the tomatoes, onion and garlic. Drizzle with remaining 2 Tbsp of olive oil along with 2 Tbsp of balsamic vinegar. Seal pouch tightly and place on grill for 5 minutes.

After about 5 minutes, add eggplant slices to the grill. Grill eggplants, turning occasionally, for 10-12 minutes, or until tender.

Meanwhile, bring stock to a simmer in a large stockpot. Once grilled, add the eggplant slices and contents of foil pouch. (Note: If onions and tomatoes are not soft at this point, leave the pouch on the grill for a few more minutes.)

Using a stick blender, puree until smooth. Stir in remaining 1 Tbsp of balsamic vinegar.

Garnish bowls with chopped parsley and crumbled feta cheese before serving.