My husband is planning on making some fermented hot sauces this summer with our pepper harvest. Instead of vinegar as a preservative, you inoculate the hot sauce with a culture (typically yogurt or kefir culture; you can find these anywhere that sells cheesemaking supplies, like a homebrewing shop) and let it ferment on its own.
More info here:
Fermented Hot Chili Sauce Recipe | Nourished Kitchen