Process feta, sour cream, onion and pepper in food processor until smooth. Refrigerate sauce until ready to serve.
Heat broiler. Spray broiler-pan rack with nonstick cooking spray. Thread pork cubes with zucchini and cherry tomatoes onto 6 (14-inch) metal skewers.
Broil skewers 5 inches from heat 10 minutes, turning skewers over halfway through cooking.
While pork is broiling, cook the couscous according to the package directions.
To serve, spoon couscous onto serving platter; top with skewers and sprinkle with parsley. Serve sauce on the side.