1. In a large resealable plastic bag, combine Farmer's Pick 100% Juice Blackberry, lime juice, olive oil, onion, jalapeno, and cilantro. Add the steak, seal the bag, and turn to coat well. Refrigerate for 2 to 4 hours. 2. When ready to serve, heat an outdoor grill or stovetop grill pan to medium heat. Remove the steak from the marinade and pour the marinade into a small saucepan. Bring to a boil and boil until the liquid has evaporated and the onions are tender, about 12 minutes. Season to taste with salt and pepper. 3. Meanwhile, pat the steak dry and very generously season with salt and pepper. Grill, turning once, until grill marks appear, 4 to 5 minutes per side for medium-rare. Transfer to a cutting board and let rest for 5 minutes. 4. Cut the steak across the grain into thin slices; cut the slices the same length as the tortillas. Divide among the tortillas and top with the onion mixture. If desired, scatter tomatoes and cilantro on top.