We doubled the recipe..thinking I was going to have some left over for 2 of us. Was I wrong. These were fantastic and really easy. Note to self: you can make these ahead of time but tossing the zucchini into a bag and leaving until ready to dump on the cookie sheet.
Drizzle vegetable oil into an aluminum or cast-iron pan, and heat the pan on the stove until the oil just begins to smoke. Add your flank steak to the pan. Cook one steak at a time. Sear each side of the flank steak for 2 to 4 minutes. Use fork or tongs to turn the flank steak once. Test the flank steak with a meat thermometer for at least an internal temperature of 145 F right before you anticipate the cooking time for your steaks to end.
Bake the flat iron steak to the desired level of doneness, checking it with a food thermometer. Cook it for about 10 minutes to 120 F for rare; about 12 minutes to 130 F for medium-rare; about 15 minutes to 140 F for medium; about 20 minutes to 150 F for medium-well; or about 23 minutes to 160 F for well done.