Pantry staples whisked together and cultured for a couple of days make a beloved condiment into a probiotic boost for many of your favorite comfort foods. Kid approved! You will never know it is fermented. Since you control the thickness and the seasoning, you can make it to your taste, too.
Add honey and apple cider vinegar and whisk into tomato mixture. Taste and adjust seasonings to your taste.
Add 1/2 C whey and whisk into your ketchup. If the ketchup is still too thick, either add more whey or add filtered water until the thickness it to your taste.
Pour ketchup into 2 pint jars and cover. Set the jars out of the way at room temperature for 1-3 days, then refrigerate. It will ferment more quickly if the temperature is warm, and more slowly in cooler temperatures.
Notes
You can collect whey from different cultured dairy projects for use in this recipe. I used whey left over from dripping milk kefir through a flour sack towel (or cheeselcoth) so that is was the consistency of cream cheese. I also sometimes drip regular yogurt so it is thicker, like Greek yogurt.If you don't have whey, or can't use dairy products, other probiotic rich liquids could work. Sauerkraut juice, or the brine from any other fermented vegetable, plain water kefir, or kombucha will provide alternatives.