Bring 15 cups of water to a boil. Add baking soda and then potatoes.
When water returns to a boil, cook for about 2-3 minutes.
Drain. Return potatoes to the pan. Add salt. Stir the potatoes around in the pot until they look roughed up a bit on the exterior. Add oil and bacon fat. Stir.
Heat oven to 500 degrees with large cast-iron skillet in it. You want the skillet very hot when you add the potatoes. Once the oven has come up to 500 degrees, add the potatoes and return it to the hot oven. Cook for 5-7 minutes. Stir. Cook for another 5-7 minutes, or until outsides are golden and potatoes are slightly puffy.
Remove potatoes from oven and toss with herbs. Serve.