How to Make It
Light the grill. In a large bowl, combine the oregano, the basil, if using, the salt, black pepper, vinegar, and oil. Add the eggplant, zucchini, bell peppers, and onion and stir to coat. Grill the vegetables in batches, turning once, until lightly browned and tender, 10 to 15 minutes per batch.
Spread the inside of each roll with 1 tablespoon of the pesto. Sandwich the grilled vegetables, lettuce, and tomatoes in the rolls.
Slice zucchini lengthwise for grilling, so that you won't have to contend with all those little rounds of squash threatening to fall through the grate.