Prepare for fermenting by washing a fermentation vessel, which can be as simple as a mason jar and lid. This recipe requires either 1 half-gallon mason jar or 2 1-quart jars. If using 2 jars, ensure that you're evenly dividing the ingredients. It does not have to be sanitized or sterilized but should be washed well with soap and hot running water. Set aside to dry. Wash fresh ingredients under cool running water.
Peel and dice 2 mangoes, slice 12 habanero peppers, dice 2 red bell pepper, peel and dice a 2" knob of ginger, dice 1 medium-large white onion, and dice 8 garlic cloves. Layer these ingredients in the prepared fermentation vessel (s).
Combine 4 cups of water with 2 tablespoons of sea salt. Stir until completely dissolved.
Pour salt brine into the fermentation vessel until ingredients are covered - if you do not have enough brine to cover the vegetables, make another batch; 2 cups water: 1 tablespoon sea salt.
Weigh down the ingredients before securing the lid tightly. Use fermentation weights, a clean ziplock bag filled with salt brine, or even a crumpled piece of parchment paper to hold the ingredients below the surface.
Set it aside to ferment.
Keep your ferment at room temperature somewhere where you'll see it daily to observe and to open the lid and burp it but keep it away from direct sunlight. If you're using an airlock lid or pickle pipe, you won't need to burp your ferment.
After a few days, you should start to notice fermenting activity. There will be small bubbles that rush to the top of the jar when you tap it, the jar may hiss slightly when opened, the color of the ingredients will dull, the brine will be cloudy, and the brine may leak over the top of the jar and run down the sides.
Allow the sauce to ferment for 7-21 days.
Once you're satisfied with the level of fermentation, strain the contents of the fermentation vessel and reserve the brine.
Blend the fermented vegetables along with ½ cup of the reserved brine, ½ cup white vinegar, and ½ cup water in a high-powered blender or food processor until smooth. I use my Vitamix and it creates a silky sauce. If using xanthan gum, add ½ teaspoon of xanthan gum to the hot sauce and blend until completely combined.
Add more brine to increase the salty flavor, more vinegar to increase acidity, or more water to cut the heat until you reach your desired flavor.
Strain the hot sauce through a fine mesh sieve to make it ultra-smooth. It takes a couple of minutes, but it's worth it.
Transfer the finished spicy habanero hot sauce to small jars or woozy bottles for storage in the refrigerator.