The recipe for this exotic salad is from "The New Greek Cuisine" by Jim Botsacos.
Preheat grill pan over high heat. Place a wire rack on a baking sheet; set aside.
Pierce each eggplant in a few places with a fork. Lightly oil grill pan with vegetable oil. Place eggplants on the grill pan and top with a heavy, flat lid, turning occasionally to prevent burning, until the eggplants are soft and the skin is black, about 15 minutes. Using a spatula, transfer eggplants to reserved baking sheet to cool.
When eggplants are cool, peel and discard the skin as well as any accumulated juices. Coarsely chop the eggplant and place it in the bowl of an electric mixer fitted with the paddle attachment. Add garlic, onion, and tomatoes; beat on medium speed for 1 minute. Add yogurt, and beat for an additional minute.
With the mixer still on medium speed, slowly add vinegar and lemon juice. When blended, with the mixer still running, add the olive oil in a slow, steady steam. Begin adding seltzer, 1 tablespoon at a time, beating until the mixture is slightly thick yet light and relatively loose. Stir in parsley and oregano; season with salt and pepper.
Transfer to a nonreactive container, cover, and refrigerate at least 8 hours or up to overnight before serving with warm pita triangles.