Make the calendula tea by steeping dried calendula flowers in boiling water, then strain. Cool the tea completely to room temperature, then weigh it out into a heatproof plastic container.
Carefully weigh out the lye, making sure you are taking all the necessary precautions with gloves, long sleeves, and goggles if needed. You absolutely do not want to come in contact with the lye at all. Make sure there are no children or pets in the area.
Pour the lye into the calendula tea. It will become very hot very fast, so be careful. Stir well, but don't breathe in the fumes.
Once the lye is completely dissolved in the liquid, leave it be and weigh out the oils, then pour them into the big pot and gently warm to about 100°F.
When both the liquid and lye mixture and the oils are around 100°F (+/- 20°F is ok), slowly drizzle the lye mixture into the oils. Rinse the lye container with cold water and set aside.
Use the immersion blender to mix the soap batter, alternating 30 seconds on and 30 seconds off.
After a couple of minutes you will notice that the mixture will start to thicken to "trace".
Once trace is achieved, pour the soap into a soap mold, cover it, and wrap it with a few blankets.
Let the soap sit in the mold for 24-48 hours before cutting.