Measure 1/2 cup of plain soy milk, then add 1/4 tsp lemon juice to it and let it sit for about 5 minutes. Don't stir it, just let the milk curdle.
Microwave coconut oil until it just barely melts (you don't want hot oil). Pour it into a blender or immersion blender container.
Add 3/4 cup canola oil, 1 tsp salt, and 2 tsp soy lecithin to the blender.
Pour the soy milk into the blender once the soy milk and lemon juice have sat for about 5 minutes and started to curd.
Blend on high for 1 minute until it is well mixed.
Pour into a glass container with a lid or into a butter mold.
Place in the freezer for at least 1/2 hour until it becomes completely firm then transfer it to the refrigerator. (It is important that it gets very cold quickly to set up correctly.)
Keep in the refrigerator for up to 5-7 days or the freezer for up to 3 months.
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Notes
I usually use plain soy milk from Aldi, but for some reason, I find that it comes out the best. Different brands of soy milk will work differently depending on their own ingredients. I have even found that the butter comes out thicker if I use the last of the soy milk in the bottom of the carton vs. soymilk from a full carton. I have also noticed that the Silk brand comes out a little thicker than other brands. (Whatever brand that you use, make sure you use plain and not vanilla flavored).
Measure out the soy milk and add the lemon juice first. This will start to curdle while you are measuring out the rest of the ingredients.
Be sure not to add more than 1/4 tsp of lemon juice or it will make your butter more of a mayonnaise consistency.
Make sure to cool butter in the freezer immediately after blending. Part of the magic happens when it cools quickly.
To make vegan stick butter
Increase the coconut oil to 1 cup instead of 3/4 cup and reduce the canola oil to 1/2 cup.
Follow all of the other ingredients and steps the same.
Pour into butter stick molds to shape your butter if desired.
How do I make soy-free vegan butter?
If you need this recipe to be soy-free, other plant-based milk will also work. The more protein in the milk, the better the consistency, so oat, pea, or hemp milk will work better. If you use almond or cashew milk, add 1 tsp of nutritional yeast to give the mixture enough protein to set correctly.
Note- to make it totally soy-free, you will also need to use sunflower lecithin instead of soy lecithin.