Season doves with salt and pepper. In a large bowl, whisk together garlic, preserves, vinegar, onions and mustard. While whisking, add oil in a thin stream until emulsified. Place doves in bowl, toss to coat, cover and refrigerate for 12 to 24 hours. Bake, broil, pan-sear or barbecue until rare to medium-rare and still juicy in the center of the breast.