Add oil, soy sauce, peach juice, minced onion and parsley to a large ziplock bag.
Add the flank steak to the bag, seal it, and lay it flat in your fridge to marinate for 3-6 hours.
Remove the bag from the fridge about 15 minutes before grilling.
Heat grill to high heat. Once the grill is hot, remove the steak from the bag of marinade (you can discard the marinade) and lay it on the grill.
Cook for 3-4 minutes, then flip to the other side and cook for 3-4 more minutes, depending on how well done you like your steak. I don't use a meat thermometer, but if you do, a general guideline is 125 to 130°F for rare, 140°F for medium rare, and 150°F for medium.
Remove steak from the grill and place it on a cutting board. Cover it with a piece of tinfoil and allow it to rest for 5-10 minutes.
Cut the meat across the grain, at a diagonal, in VERY THIN slices (almost "paper thin"). ENJOY!
Peach Juice: White grape juice, pear juice, apple juice. You could even use one (14 oz) can of sliced peaches and puree the entire can--peaches, juice and all.Variations:
Marinated Flank Steak Fajitas: Slice a couple bell peppers and an onion and season with salt and pepper. Cook on a very hot skillet or grill pan with oil for a few minutes. Serve flank steak and grilled vegetables in a warm flour tortilla topped with Pico de Gallo, guacamole, sour cream, and garnish with cilantro.
Marinated Flank Steak Tacos: Serve flank steak in a warm corn tortilla topped with Pico de Gallo or 5 minute salsa, avocado, and other favorite toppings.
Steak Salad: Serve on a bed of greens, with red onion, avocado, cherry tomato, cucumber, grilled corn, gorgonzola or bleu cheese.