Those who barbecue usually do it for direct grilling. This means that you barbecue the meat or the fish directly above the flame, usually at very high temperatures or that you grill the meat or fish through the direct radiant heat of the flame on your barbecue. Direct grilling is good for quickly preparing smaller or thinner slices of meat or fish, or to scorch bigger pieces of meat.
With indirect grilling the meat or fish is not grilled over the flame but next to it. Ideally, indirect grilling is done on a barbecue that is closed. The meat or fish is grilled next to the direct radiant heat of the flame. To do this, you should use a big barbecue grill, so that you can lay the fish or meat nicely next to the direct heat of the charcoal. Your piece of meat or fish will be grilled through the gasses from the smoke which are in your barbecue. The best way of indirect grilling is at a medium temperature.
You can use indirect grilling both with a charcoal barbecue and a with a gas barbecue. With a charcoal barbecue, wait until the coals glow and then rake one half of the coals to the left and the other half to the right of the barbecue pail. Put a bowl in the middle - among the charcoal – to catch the grease and lay your piece of meat or fish on the grill above it.
With a gas barbecue you need to turn off certain burners. If you have two burners, then you should turn off one of the two and then put the meat or the fish above the burner which is not burning. If your gas barbecue has 3 burners, then turn off the middle burner and lay your piece of fish or meat above it.
By indirect grilling you can cook bigger, thicker or more tender pieces of meat or fish slowly, without running the risk of burning your entrée. An extra advantage is that your entrée will be evenly cooked and there will be no raw pieces.
Simply said, direct grilling is equal to the grill function of your barbecue and indirect grilling is equal to the oven function.