Tacos al carbon

1 1/2 lbs flank steaks 3 -4 cloves garlic , minced 3 limes, juice of 1 lemon, juice of (juice of both lemon and lime should equal 1/2 cup) 2 tablespoons[...]

2 medium white onions, sliced into 1/2 inch rounds (keep the rounds intact for easy grilling) 3 garlic cloves (peeled and roughly chopped) 3 tablespoons fresh[...]