• Place flank steak in a large (9 x 13-inch) baking dish.
• Whisk together orange juice, lime juice, olive oil, salt, garlic powder, cumin, and oregano. Pour over steak. Cover and chill for at least 1 hour (or up to 8 hours), turning occasionally.
• Remove steak from marinade. Discard marinade.

GRILL INSTRUCTIONS:

• Prepare a hot fire by piling charcoal on one side of grill, leaving other side empty. (For gas grills, only light one side.) Place food grate on grill. Place steak on lit side of grill. Grill, covered with grill lid, over medium-high heat (350° to 400°) about 20 minutes, flipping halfway through. If you are cooking a smaller flank steak (about 1 lb.), it may only need about 15 minutes on the grill.
• The steak is done when the edges are charred and crispy, and you see some nicely dark searing on the top. Check the temperature in the thickest part with an instant-read thermometer: 115 to 120°F for rare steak, 120 to 125°F for medium-rare steak, 130 to 135°F for medium steak, and 140 to 145°F for medium-well steak.
• Let stand 5 minutes before slicing against the grain and serving.

OVEN INSTRUCTIONS:

• Heat your broiler to HIGH.
• Place an oven rack a few inches below the broiler. Line a broiler pan with aluminum foil, add the broiling rack, and spray with nonstick cooking spray.
• Place marinated steak on prepared broiler pan. Slide it directly under the broiler.
• Cook for 4 to 6 minutes, flip it over, and broil for another 4 to 6 minutes (8 to 12 minutes total).
• The steak is done when the edges are charred and crispy, and you see some nicely dark searing on the top. Check the temperature in the thickest part with an instant-read thermometer: 115 to 120°F for rare steak, 120 to 125°F for medium-rare steak, 130 to 135°F for medium steak, and 140 to 145°F for medium-well steak.
• Let stand 5 minutes before slicing against the grain and serving.