Gently pound cutlets to 1/8 -inch thickness between 2 sheets of plastic wrap with flat side of a meat pounder or with a rolling pin. Cut into 2-inch-wide pieces and season with salt and pepper.

Put flour in a large shallow bowl. Lightly beat eggs in another large shallow bowl. In a food processor, finely chop bread crumbs, fennel, celery leaves, parsley, marjoram and thyme; transfer to a third bowl. Lightly coat veal pieces, 1 at a time, with flour, then dip in egg, letting excess drip off, then dredge in bread crumbs, coating completely, and put on a sheet of wax paper.

Heat 3 tablespoons oil in a large nonstick skillet over medium-high heat. Fry veal pieces in batches (adding more oil as needed), turning over once, until golden and just cooked through, about 6 minutes total. Transfer to paper towels to drain.

In a small bowl, toss together zucchini, remaining tablespoon oil, and generous pinch salt and pepper. In a second bowl, stir together mayonnaise and pesto. Spread 2 tablespoons mayonnaise mixture on bottom halves of rolls. Make sandwiches with baby lettuces, veal, a little more mayonnaise mixture and zucchini.