Hello fishaspey! I'm glad you found my guides to be useful! That's what they're there for.
No, I never make sparkling sake. Call me a purist if you want, but I like my sake to be perfectly clear, perfectly still, and alcoholic as hell.
But hey, I'm not judging, that's just my preference. If you liked how it came out, then go ahead and duplicate it!
Now...how to duplicate it? Well, I don't have much in the way of details about the process you used for that batch. A lot of questions are left unanswered. Did you build up the
moromi or was that first attempt a
doburoku? Did you take a specific gravity measurement at any time? Obviously it wasn't finished fermenting and you didn't pasteurize, which left yeast and other wild critters alive to gobble up the residual sugar and carbonate those bottles.
The green
koji flavor was present because you skipped pasteurizing. Once you pasteurize the sake, that flavor is driven off. I'm okay with that because I don't like the pungent green
koji character in a sake. Again, this is my personal preference.
If I were to set out to make a carbonated sake, I would personally go with forced carbonation so that I wouldn't have to skip the pasteurization and fining processes. However, skipping pasteurization, diluting the sake, and priming for bottling
is an option. Just be sure you keep those bottles as cold as you can get them (shy of freezing, of course) to prolong their shelf life. Even so, that sake is eventually going to go sour due to spoilage organisms left alive in the bottle. You might get a month out of those bottles in the coldest part of your refrigerator.