Assemble your ingredients, equipment, and safety gear.
Make sure kids and pets can't access the area you're working in, and you're able to devote your full attention to making soap.
Prepare your mold.
Weigh out the water into the 1 quart mixing container.
Make sure you have on gloves and goggles.
Weigh out the lye into the small cup.
Sprinkle the lye into the water and stir until completely dissolved. There will be momentary strong fumes released that you don't want to breathe in.
Set the lye solution aside in a safe spot to cool.
While the lye solution cools, melt the coconut oil in a small saucepan.
Weigh the olive oil into the larger mixing container, and add the coconut oil once it's melted.
When the lye solution is around 90 to 115 degrees F, pour the lye solution into the container of warmed oils. (You don't have to have the oils and lye solution the same temperature - it's okay if the oils are a little under 90 degrees.)
Use the immersion blender (stick blender) to mix the oils and lye solution together in a few short bursts.
Add the ground oats and diluted honey. If adding the extra oil, do so now too.
Stir by hand a few seconds, then burst the stick blender a few seconds. Alternate hand stirring and the stick blender. Don't run the immersion blender continuously.
Mix until you reach trace. Trace means when you drizzle a small bit of the soap mixture over the surface of itself, it will leave a faint pattern or 'trace' before sinking back into the mixture.
Pour into your soap mold. Because this soap has honey, it may heat up quicker than other soap. Cover lightly with a piece of parchment paper and then a light piece of cloth, like a pillowcase or dish towel.
Keep the soap covered, but peek at it every so often. If you see a crack forming in the top, it's getting too hot and should be uncovered. You may also want to place it on a cooling rack to allow cooler air to circulate underneath.
Keep the soap in the mold for at least 24 to 48 hours.
Unmold and slice into bars right away, or if the soap is on the soft side, you can wait a few days before cutting into soap bars.