In a large stainless steel pot, combine tallow, olive oil, coconut oil, and avocado oil over medium to low heat. Heat until melted and then move off of burner and allow to cool until 90 degrees Fahrenheit.
Using gloves and goggles, measure lye by pouring it into a zip close bag on a kitchen scale. Set aside and weigh water. Take both outside. Put on a charcoal mask and pour lye into water and stir until it is dissolved. Do not breathe in the fumes. The chemical reaction will end and the fumes will dissipate in a few minutes. Allow to cool to about 90 degrees Fahrenheit.
3.4 ounces lye, 8.2 ounces water
When both oils and lye water has cooled, pour lye water into the pot of oils and blend with a stick blender on and off until light trace (It begins to thicken. Learn more about trace here.).
Add molasses, cinnamon, and essential oils and blend until mixed well.
Pour soap into a prepared mold (lined if necessary). Use a rubber spatula to scrape well. Cover. Insulate with towels if your home is cool.
After 24 hours, remove from mold and cut into bars. If soap is still very soft, leave it in the mold for 12-24 hours and check again. Cure bars in a cool, dry place for 3-6 weeks to harden.
Notes
Vegan Recipe Alternatives. Remember, if you have ingredients for one recipe, or want to use your favorite vegan recipe, you can always use scents and colors from another recipe. Essential oils can be interchanged in similar quantities without making any other change to the recipe.