After marinating the steak in beer, drain the beer and pour carne asada marinade over steak, turning to coat all over. Return to refrigerator, covered, to marinate for 3 hours.
Start your grill. Use the highest heat possible. The grill should be smoking, blistering, searingly hot. Grill marinated steak as follows: For skirt steak, 3 minutes per side. For flank steak, 5 minutes per side. NOTE: Cook time depends on steak thickness and desired doneness. Remove cooked meat from heat, and allow it to rest for 5 minutes before serving.
While meat is resting, grill the tortillas on each side until slightly charred. Slice carne asada steak thinly across the grain.