MICROWAVE links as directed on package; coarsely chop links. Pour egg product into small bowl; stir in links. Pour into nonstick skillet.
COOK on medium heat 3 to 5 min. or until egg product is set, stirring occasionally. Meanwhile, mix mayo, yogurt and mustards in microwaveable bowl. Microwave on HIGH 1 to 2 min. or until warmed, stirring after each minute.
COVER muffin halves with tomatoes, egg mixture and sauce; sprinkle with parsley.