Sterilize a pint-sized mason jar, along with its lid and band by boiling it for 8 minutes. Let the jar and lid air dry and cool on a clean wire rack.
Slice the red peppers in half and remove the stems. To reduce heat and avoid bitterness or gritty texture, remove the seeds and any white ribs or pith using the tip of a knife or a sharp metal teaspoon. Wear gloves to avoid irritation from the peppers.
Add the prepared peppers, minced garlic, sugar, salt, and water to a blender. Blend until a semi-smooth purée is achieved. Transfer the purée to a clean, sterile jar, tighten the cap, and let it ferment in a clean jar on the counter, away from direct sunlight.
Burp the jar every 24 hours by slightly unscrewing the lid to release built-up gases, then re-tighten. After 2-4 days, when the peppers are sweet, hot, and complex, proceed to the next step. Never taste the sauce by using anything other than a very clean metal spoon so as not to introduce contaminants during fermentation.
In a blender, combine the fermented pepper sauce, unseasoned rice vinegar, and apple cider vinegar. Blend until smooth. Strain the mixture through a fine mesh strainer, or a nut-milk bag into a large saucepan.
Heat the strained sauce over medium heat. Once it comes to a boil, lower the heat and let it simmer for 6-8 minutes until slightly thickened and bubbling. Simmering for a little longer will make the sriracha more stable and extend its shelf life, though it will dull its vibrant red color.
Remove the saucepan from heat and allow the sauce to fully cool to room temperature. Using a funnel, pour the hot sauce into a sterile bottle. Store your homemade sriracha in the refrigerator, where it will keep for up to three months if properly stored and not brought into contact with unpasteurized food contaminants.