For the Creamy Greek Dressing: Stir together yogurt, sour cream, lemon juice, garlic, oregano, salt and pepper in small bowl until well combined. Stir in enough milk to desired consistency. Cover and refrigerate until serving.
Place spinach, tomatoes, cucumber and onion in very large salad bowl. Gently toss to combine. Cover and refrigerate while preparing pork.
Combine Greek seasoning and salt; sprinkle and rub evenly over pork. Cook half of the cutlets over medium-high heat in large skillet coated with nonstick cooking for 2-3 minutes or until tender. Transfer cutlets to cutting board. Remove skillet from heat and recoat with cooking spray. Cook remaining cutlets. Cut cutlets crosswise in half.
To serve, divide spinach mixture among 4 plates. Arrange 1/4 of pork on each salad. Drizzle 2 tablespoons dressing over each salad. Sprinkle with black pepper, if desired. Serve with remaining dressing.
Note 1: If Greek Seasoning is unavailable, substitute 2 teaspoons dried oregano leaves, 1/4 teaspoon garlic salt, 1/8 teaspoon onion powder and 1/8 teaspoon kosher salt for the 2 1/2 teaspoons Greek seasoning and 1/4 teaspoon kosher salt.
Note 2: To cook cutlets in a countertop grill with lid, preheat grill according to manufacturer’s directions. Sprinkle and rub Greek seasoning-salt mixture over both sides of cutlets. Place cutlets on grill; close lid. Cook for 1-2 minutes or until tender.