The origin of marshmallows is a little unclear, but definitely included either the root or stem of the medicinal marshmallow plant, and a lot of sugar. These original marshmallow confections were, of course, vegetarian, because they used the natural mucilage of the marshmallow plant instead of the natural bones and skins of the pig, cow, and fish animals. For a while I've been wanting to try making these original marshmallows. I found a recipe for "marshmallow treats" that uses marshmallow root, through it is about half egg whites so it isn't vegan.
2 egg whites
1 t. vanilla extract
½ c. sugar
1 T powdered marshmallow root, soaked in a bit of water
Marshmallow root often comes roughly chopped, so you can use a coffee grinder to turn it into powder. Soak the powdered root in some water until it gets mucilagey.
Use an egg beater to beat the egg whites until they are pretty stiff with little peaks. Add vanilla and then whip some more. Then whip in the sugar, a bit at a time. Mix in the marshmallow goo. The fluffy egg/sugar mixture will almost instantly turn gooey, just like the inside of modern commercial marshmallows or marshmallow fluff--pretty cool--too bad it has egg or I would just eat it like that. I baked the treats like cookies. A muffin tin works well to retain the shape of the treats. The recipe says to bake them for an hour. I tried taking some out after 15 minutes and 45 minutes too. The 15 minute ones shriveled up and were still a bit gooey but the ones in there longer lost all gooeyness and ended up being sweet airy cookies, with the taste of marshmallow root.
Making and eating these was fun--I brought them to a camping-themed potluck and made smores and weirded people out--but I don't think I would do it again. Watch out for bits of marshmallow root that didn't get fully pulverised. Maybe I'll find an even more original recipe sometime. From the wikipedia article, it sounds like boiling the pith of the stem is the way to go.