For the dressing, in a medium bowl whisk together lemon zest, lemon juice, canola oil, yogurt, vinegar, tarragon, honey and mayonnaise.
Cook pasta just past the al dente stage according to package directions. Rinse under cold water; drain. Place pasta in a large bowl.
Meanwhile, heat olive oil in a large skillet over medium-high heat. Add mushrooms; cook and stir 4 to 5 minutes or until softened. Add mushrooms to bowl with pasta. Stir in peas, celery and onion. Drizzle with 1/2 cup of the dressing; toss to combine.
Coat grill rack with nonstick cooking spray. Preheat grill to high (400°F to 450°F). Season steaks with salt and pepper to taste. Grill 4 to 5 minutes per side (145°F for medium-rare) or to desired doneness. Transfer to a platter; let stand 5 minutes. Place steaks on individual plates. Serve with pasta salad and (if desired) additional dressing.