Whisk together lemon juice and next 3 ingredients in a large bowl. Add tomato and next 3 ingredients; gently toss to coat.
Reserve seasoning packet from tabbouleh salad mix for another use. Pour tabbouleh mix into a large bowl; stir in 1 cup boiling water. Cover and chill 30 minutes. Stir in tomato mixture. Cover and chill 1 hour. Top with feta cheese, and season with salt to taste.
Note: For testing purposes only, we used Near East Taboule Mix Wheat Salad.