Sprinkle tilapia with pepper and salt. Place flour in a shallow bowl. In second shallow bowl, combine salad dressing and yogurt. In a third shallow bowl, combine the bread crumbs, garam masala, cumin and cayenne. Dip fish in the flour, dressing mixture, then bread crumb mixture.
In a large nonstick skillet heat oil over medium-high heat; cook fish in batches until fish just begins to flake easily with a fork, 2-3 minutes.
Meanwhile, for sauce, place the yogurt, cilantro, cumin and salt in a food processor; cover and process until blended. Stir in cucumber and onion. Serve tilapia with spinach, mango and prepared sauce.