1Prepare the falafel as directed. Prepare the yogurt sauce and refrigerate until ready to use.
2In a frying pan, warm the olive oil over medium-high heat until it is nearly smoking. Add the eggplant in a single layer and fry until golden, turning once, about 4 minutes. (You may need to do this in two batches to avoid overcrowding). Using a slotted spoon, transfer to paper towels to drain. Season with salt and pepper.
3Pour off all but a couple tablespoons of the oil. Add the onion and peppers and cook, stirring occasionally, until tender and slightly browned, about 10 minutes.
4Stuff the pita bread halves with falafel, eggplant, peppers, and onions. Top with the yogurt sauce (or plain yogurt) and serve.