Cut off the top and bottom parts of the rhubarb stalk. Dice the rhubarb into 1/2 inch cubes. If the outer layer is too tough, you can peel that off and discard it.
Use a large frying pan over medium heat, add all of the ingredients.
Cook it until it starts to steam and then reduce the heat to a simmer.
Stir the rhubarb to combine all the ingredients.
After about 10 minutes the rhubarb will start to soften. You should be tender enough to smash with with a fork.
Take a small spoonful and cool it down. Taste a small amount of the sauce to make sure it is at the sweetness you prefer. Be careful because it's really hot!
Add more sweetener if needed. Using a spoon mix the sweetener in until it's fully incorporated.
The texture if the sauce will depend on how you like it also. If you prefer a chunky texture, you can leave it as is when it's done cooking.
If you prefer a smooth sauce, I would allow the sauce to cool slightly and add it to a blender.
Blend the rhubarb sauce on high for 30 seconds.
Pour the rhubarb sauce into mason jars. Leave the jars uncovered until it fully cools.
Add the lids to the mason jars and store the rhubarb sauce in the refrigerator for up to two weeks! The lemon juice in this recipe helps keep it fresh longer.
Notes
1/2 cup allulose = tart
3/4 cup allulose = semi sweet
1 cup allulose = sweet
Feel free to use any keto sweetener you want but be sure to taste the sweetness and start off adding a lower amount till you get to the sweetness you enjoy.