Flat iron steak is an inexpensive but totally flavorful cut of meat, especially when marinated in a citrus adobo sauce to make my favorite steak tacos.
Poke holes in the steak with a large knife, taking care to make the holes with the grain. Add the steak to a gallon size freezer bag.
Add the orange juice, garlic cloves, chipotle peppers and adobo sauce, cilantro, cumin, cinnamon and kosher salt into a blender. Puree until smooth then pour into the freezer bag with the steak, seal and refrigerate for 1 hour up to overnight.
Let the steak come to room temperature before grilling, about 20 minutes. Oil grates with grapeseed oil and preheat it on high heat.
Reduce the heat to medium-high and grill the meat for 10 minutes on each side or until cooked to desired doneness.
Allow the steak to rest on a platter, covered with foil, for 10 minutes before cutting.