In a medium saucepan, mix the water with the stevia and vanilla extract.
Add the cranberries. Bring to a simmer over medium heat (this should take about 3 minutes).
Lower the heat to medium-low to keep a consistent simmer. Cook, uncovered, stirring occasionally, until the cranberries are soft and starting to burst, about 10 minutes.
Remove the saucepan from the heat. Taste the sauce and decide if its level of tartness suits you or if you’d like to add more stevia. I sometimes mix in an additional 1 teaspoon of stevia at this point (which equals ⅓ cup sugar).
Cool to room temperature before serving.
If using a granulated sweetener instead of stevia, use a powdered sweetener to prevent it from crystallizing as the sauce cools down.Here are a few ideas for changing up this recipe:
You can use frozen cranberries if you can't get fresh ones.
Orange zest, added to the water mixture, greatly enhances the flavor of the sauce. And since we're trying to keep this cranberry sauce keto, it's a better option than using orange juice instead of water, which is very tasty but adds quite a bit of sugar.
Some people like adding a cinnamon stick. Personally, I'm not a fan, but if you think you might enjoy the flavor combination, go ahead and give it a try!