However, itâs also a time to be aware of the dangers soaring temperatures can bring. Extreme heat is the number one weather-related killer in the U.S, claiming more than 650 lives across the nation each year, according to the Centers for Disease Control and Prevention.
1 In a bowl whisk together garlic, extra virgin olive oil, balsamic, 1/4 cup red wine, 1 tablespoon chopped rosemary, salt and pepper.  Place flat iron steak in a resealable plastic bag. Pour marinade over the top. Shake to coat steak in marinade. Refrigerate for 8 hours or overnight.
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.