Make pasta according to package instructions. Drain and run cold water over pasta. Place in a large bowl.
In a glass measuring cup or small bowl, add greek yogurt, mayonnaise, red wine vinegar, Dijon mustard, oregano, garlic powder, salt and pepper. Mix well to combine.
Stir in tomatoes, cucumber, onion, and bell pepper with the pasta. Mix well.
Add the greek yogurt mixture and mix well.
Refrigerate pasta salad for a minimum of 3 hours to overnight.
Serve cold or at room temperature.