2) Add the cheese and pulse on and off until just combined. With the motor running, slowly add the oil through the opening in the cover, processing to a smooth, thick sauce.
For the beef crostini:
1) Spread 50g of the pesto evenly onto each beef steak. Place the steaks in a dish, cover and marinate in the refrigerator for 15 minutes to 2 hours. Cover and refrigerate the remaining pesto.
2) Preheat a charcoal barbecue to a medium heat. Place the steaks on the griddle over medium, ash-covered coals. Arrange 12 bread slices around the steaks.
3) Griddle the bread slices 2 to 3 minutes or until lightly toasted, turning once. Remove the bread from the griddle, then repeat with the remaining 12 bread slices. Meanwhile, griddle the steaks, covered, for 11 to 14 minutes for medium rare to medium, turning occasionally.
4) Spread 2 tsp of the remaining pesto on each toasted bread slice. Carve the steaks into thin slices and place evenly over the bread slices. Divide the cheese and chopped coriander between each slice. Serve immediately.
2 (225g) beef shoulder top blade (butler's) steaks or 4 beef fillet steaks, cut 2.5cm thick, may be substituted for chuck steaks. Griddle shoulder top blade steaks, covered, over medium, ash-covered coals for 10 to 14 minutes (over medium heat on a preheated gas griddle, covered, 12 to 16 minutes) for medium-rare to medium, turning occasionally. Griddle fillet steaks, uncovered, over medium, ash-covered coals for 13 to 15 minutes (over medium heat on a preheated gas griddle, covered, 11 to 15 minutes) for medium-rare to medium, turning occasionally.
Grated Parmesan cheese may be substituted for the Cotija cheese.
For less heat, remove the seeds from the chipotle peppers.