Season cutlets on both sides with 1/4 teaspoon each salt and pepper. Place flour on a large plate; dredge the cutlets, shaking off excess.
Heat 2 teaspoons oil in a large nonstick skillet over medium heat. Add half the cutlets and cook until golden brown and just cooked through, 1 to 3 minutes per side. Transfer to a platter; tent with foil to keep warm. Add 2 more teaspoons oil to the pan and cook the remaining cutlets. Transfer to the platter.
Add the remaining 2 teaspoons oil to the pan. Add leeks and cook, stirring occasionally, until soft and light brown, 6 to 8 minutes. Stir in broth and garlic; bring to a boil, scraping up any brown bits, and simmer for 2 minutes. Stir in capers, lemon zest, lemon juice, parsley and the remaining 1/4 teaspoon each salt and pepper. Return the veal and any accumulated juices to the pan. Cook, turning the veal to coat with the sauce, until heated through, 1 to 2 minutes. To serve, divide veal among 4 plates and top with the leek mixture.