Add carrots, onion, vegetable shortening, coconut oil, olive oil, and mushroom seasoning to a pot. Put on medium heat with no lid, then lower it as soon as you see bubbles.
Let cook for about 25 minutes until fragrant and the color is a deep orange.
Strain through a cheesecloth and gently squeeze to remove the oil. Use the extra bit of carrots and onion for another dish (It's really great on toast)
Peel the golden potatoes and put them in water. One by one, slice into even slices either by hand or by mandolin. You want it thin enough you can see your fingers. About 1/16".
Drain the potatoes and pat them dry. Then pour the vegan duck fat in a bowl and add the potatoes, along with salt. Mix it thoroughly with your fingers until everything is coated and they are not sticking together.
Preheat oven to 250°F
Line a loaf pan with parchment paper and layer the potatoes in even layers. Push on the top of it with your fingers and put in the oven to bake for 3 hours.
After 3 hours, check if it's cooked through by inserting a knife in. If there is no resistance, it's ready.
Put something heavy on top, like another loaf pan with mason jars filled with water on top.
Leave overnight in the fridge for 10-13 hours.
Take out and slice into rectangles. You want it to be so you will ba able to pick it up and dip it afterwards.
Heat up your oil for 375°F and fry your potato pieces 2-3 at a time. Fry until golden brown at all sides. Once you take it out season immediately with flaky salt
Serve hot and with a dipping sauce of choice.