How can I barbecue salmon steak?
Buy a cedar plank. Soak it in salted water for a couple of hours

Rub the salmon with olive oil and season it with a little bit of salt, I use kosher salt or smoked sea salt but regular table salt will work just fine. Then put the salmon on top of the plank, skin side down. Then put the plank on the BBQ. You can see the fish cook, it will get pinkish-white starting from the skin and traveling up. If your grill has a top, close it and cook for about 20-30 minutes. Check it to make sure it's not drying out. Internal temp should be around 130 or so.