Perhaps a stream of hot oxygen-free gas on buds - steam distillation but with something other than steam. That would be far out. Other than that, how can you get high THC with no solvents at any point - and - few GC peaks? Kugelrohring hash might accomplish this. Ice hashes shouldn't count as using water even if it does count. Assuming ice hash would be a more economical and reliable source than dry sift, unless you happen to have super sized tumblers in the basement.