cook pasta according to package directions until tender but still firm to the bite. Drain and rinse under cold water for 30 seconds. whisk together mayonnaise, yogurt, and vinegar in a small mixing bowl. season to taste w salt and pepper. place tuna in a large mixing bowl and break into small pieces. add pasta, celery, tomatoes, peas, and onion; stir to combine. Add dressing and stir to combine. Season to taste with salt and pepper and refrigerate until ready to serve.