Author of the open sauce here. Coolt to see this on HN for the second time(!)
Still making fermented sauces and pickles. Set Moroccan Salted Lemons this week actually.
Happy to answer any questions. :-)
Habeneros aren't common there, but in general for cheap chilis, try the Turkish grocery stores (EuroGida or similar). Basically for any Mexican / Latin-American stuff, they're great for sourcing ingredients: chilis, dry beans, corn meal, flour tortillas (durum) and will be a lot cheaper than specialty shops. Chilis are also easy to grow (I'm growing 4 kinds on my balcony in Berlin), and one habanero plant goes a long way.
Not in DE myself but scotch bonnet chillies are more easily found in the UK due to the Carribbean/West African connection. You may have a better chance of finding them instead and I'm told they are quite similar.
Usually you can find them at super markets (Rewe, Edeka) sometimes Discounter have it as promotional item (Aldi).
I recommend growing yourself just use seeds from the bought fruits. They are rather easy to grow.
I can also send you seeds, if you like.
I love this recipe, I'm so happy you made it available. I have made it multiple times. I might suggest you let potential chefs know of possible increased gastric activity with fermented foods, especially ones that like to give you painful reminders on the way out. But I'm sure as hell not submitting a pull request for that :)
This is really, really important for any kind of fermentation (including things like sourdough starter). I believe it's possible to get rid of some kinds of chlorination from municipal water sources by boiling the water first, but it is not possible to get rid of "chloramines," which are widely used (at least in the US). The web page for your local water supplier should be able to tell you whether they use chloramines or not, but I pretty much always just use bottled water that I know has nothing in it that would inhibit the fermentation.
It may be what's used in dechlorinator products, but vitamin C (ascorbic acid, or Sodium Ascorbate) does a good job of converting chloramines (or just chlorine) to salt, NaCl. I used an ascorbic acid shower filter for years when living in a city that used chloramine in their water. It worked well and I could tell every five months or so that it needed to be refilled because my skin started itching from the chlorine.
You can also buy dechlorinator for use with aquariums - super important to not accidentally kill the bacteria maintaining your nitrogen cycle. A bottle goes a very long way (ratio is drops per gallon of tap water).
My sourdough starter is absolutely fine with chloraminated water. I do use bottled water for pickles though because each batch is starting from scratch.