Its that time of year here in the US of A that sweet potatoes are on sale, so I thought about making a beer with them. I found this https://youtu.be/rwcEllQZpLE
Any fermented, malted starch drink is technically a beer. Chicha which is made entirely on corn is an ancient native Americas drink; many South-East Asian countries make rice lagers or ales; authentic ginger beer ferments raw sugars and ginger; gluten-free beers are often made with rice, sorghum, quinoa or other non-wheat and non-barley grains. There’s a plethora of different beers out there made with very different ingredients that all share the same brewing process.
So, yes, as long as you were able to malt the sweet potato to induce sugars that you then ferment using yeast without distillation, you’re producing beer.
Yes. You can mash (as in enzymatically convert starches to sugars, not as in mashed-potatoes) any gourd (think pumpkin, squash, potatoes, sweet potatoes). They tend not to add too much noticeable flavor to a beer (just a general earthiness and some color contribution) so it's often recommended to oven roast them a little first to get some caramelization. Here is a recipe that uses sweet potatoes.
I sometimes use sweet potato for beer in a similar way as I do pumpkin. Just clean it up, shove it in the oven until it caramelizes a bit, mash it with a fork or whatever is at hand and add it to the mash - I usually use 1-2 kg (~2-4 lbs) for a 20L (5 gal?) batch. And from then on it's brewing as usual. Gives a nice colour to the beer though I can't say I've noticed any flavour.
Read about being able to mash them on their own, but I've yet to try that, not sure how I would go about it.
Not quite the same but there’s a place in Denver that makes sweet potato vodka. So… I guess fermenting them works, which isn’t surprising. Since it is vodka it doesn’t really have a flavor of course.