In a small bowl, mix together the Greek yogurt, cream cheese, herbs, sun-dried tomatoes, and a pinch of salt. Toast the bagel, if desired. Spread the cream cheese mixture on the bagel and top with turkey, red onion, lettuce, and any other low-calorie toppings you like. Serve.

Meal prep tip: For best results, prepare the sun-dried tomato cream cheese spread ahead of time and assemble the sandwich the day of eating. However, the fully assembled sandwich can also be made up to a few days in advance: wrap tightly in foil and store in the refrigerator until ready to eat.