For cold smoking I use a UFO smoke generator https://www.youtube.com/watch?v=Tv7zYhpGCec Smokai do one also, both Kiwi made & very easy to use. So much easier than shagging around with a firebox and you cannot accidentally hot smoke the fish and you have control over smoke output. You can convert anything (44 gallon drum, tea chest, barby etc) into a decent smoker with one of these. For fish I buy pohutakawa sawdust nice and mild Manuka is much stronger in flavour. For brining you can either just use uniodized salt or salt/brown sugar and pack it between fillets and then wash off and dry technique or make a brine. Brine fish then wash in running fresh water, cut a bit off microwave it and test for saltyness every hour or so when happy dry off to form pellicle and smoke. There's heaps of youtube instructionals etc. I have a cheap vacuum packer to freeze the final product, you need to be careful not to knock the finished items around in the freezer as the cheap vacpac plastic is fragile, they pop and you end up with freezer burn. It's a fair bit of dicking around maybe practice with some kahawai or speckled mud fish before you launch into a marlin but once you get hang of it it's not too bad.
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