Pat halibut dry with a paper towel. Drizzle 1/2 tbsp of vegetable oil on each side, and use your hands to make sure the steak has a light even coat. Season each side with salt and pepper.
Melt butter in a small bowl, stir in black urfa chili and a pinch of salt, and set aside by the grill for basting.
Start your grill and prepare so you can cook your fish directly over the flame or hot coals. Clean and lightly oil your grill grate with the remaining vegetable oil (I recommend folding up a paper towel, covering one side in oil, pinching the paper towel in your grill tongs, and quickly rubbing oil onto the grate just before adding the fish).
Lay halibut steak directly over hot coals. Grill, flipping after 4-6 minutes depending on the heat of your grill, once the first side is nicely browned. Brush the cooked side with chili butter while the other side cooks. After another 4-6 minutes, the bottom should be cooked and the internal temperature should reach 130 degrees.
Flip once more and brush chili butter on once again, then remove from heat. Let sit for 5 minutes, then season again with salt and pepper to taste, squeeze lemon wedge over your fish, and enjoy.