Cook pasta according to package, add 1/4 teaspoon salt and during the last 3 minutes, add the cut green beans. Drain and run under cold water.
Drain salmon and break into chunks. Combine the pasta, carrots, green beans and salmon in a bowl.
In a food processor, mix together the cottage cheese, yogurt, lemon juice, onion, mustard and dill. You want a smooth sauce. Pour sauce over pasta and chill before serving.