Minecraft wiki entry for Nether_survival, associated text: Another possible method is to take any flammable block and place it on one side of the block. By getting lava close to the flammable blocks, the lava can eventually light the wood, thus lighting the portal frame. Having the lava right on the opposite side of the frame of the flammable block is the fastest method. Also, the higher the difficulty, the faster the blocks catch on fire, so this method is more difficult in Easy or Peaceful difficulties. If the player also lacks a bucket, one can channel lava past the portal, or even build a trail of flammable blocks (planks are cheap, but wooden slabs are cheaper) to the nearest fire. That last method is especially tricky, as fire doesn't always catch. If this happens, try making it wider than one block.