Dry stacked (yes, even though it's wet). The next step is a fiber-reinforced coat, then fill the interior cavities with rebar and more mortar/cement mix. The cavity behind will be insulation, probably perlite.
The half-blocks I cut with a cut-off saw and an abrasive blade. Took about 3 minutes per block. Later on I discovered that the 5HP grinder with the diamond blade cuts through them like butter. The difference in color is because the half blocks are still damp from being cut.
Dry stacking is a bit of a misnomer. There is a little bit of mortar in the joints.
Less than two hours including prep, cutting, and cleanup.