You heard me right—these are marshmallows with no gelatin that vegetarians can take camping. At least, I'm pretty sure they'll work based on preliminary toaster-oven-based investigations, which yielded toasty-on-the-outside, gooey-on-the-inside balls of sugary goodness. Looking forward to trying them for real next weekend!
I spent a very long time choosing a recipe for this project. Not because there aren't a lot of vegetarian marshmallow recipes on the internet, but because most of them say they're not s'mores-friendly. Which is the only point of making marshmallows, right? I ended up going with this one partly because it seemed prudent to choose one with egg whites (no need to be vegan today) and partly because I found xanthan gum in cheap little packets at the end of the health supplement aisle at Berkeley Bowl. Plus, it's a nice easy recipe, especially if you're familiar with meringue buttercream frostings (although it's more like the Italian variety, which I haven't made, than the Swiss kind, which I have).
I followed the recipe at this blog. That, in turn, follows this cool collection of guidelines and recipes for many intriguing (and many more just plain odd) molecular gastronomy gelled edibles: dondurma! Iberian ham cream! whiskey gel! restructured onions! Definitely worth a look.
This makes 25 jumbo-sized (~1.5"x1.5"x1") marshmallows, big enough that you only need 1 per s'more. I used cornstarch for all the dusting, which gave the marshmallows a bit of a cornstarchy taste. I suspect that powdered sugar would work just as well and taste much better, so I'd advise trying that instead, but I can't totally vouch for it. Also, even with all that cornstarch, the marshmallows are sticking to each other a bit after one night in the fridge; I plan to re-dust them right before heading out for camping.
1 t xanthan gum
1 T + 1.25 c sugar (250 g)
4/5 c corn syrup (250 g)
1/4 c water (60 mL = 60 g)
1 t vanilla
3 egg whites
lots of cornstarch (or wherever I say cornstarch, sub powdered sugar)
Butter the bottom and sides of a 8x8" square pan and dust thoroughly with cornstarch. Grind the xanthan gum with 1 T sugar and set aside (since the xanthan gum is already a powder, I can only assume that the point of this step is to make the sugar finer). Weigh out the remaining sugar and the corn syrup in a 2-quart saucepan, then add the water and vanilla.
Heat the contents of the saucepan to 240-250F (firm ball), stirring at least after it foams up (220F). Meanwhile, or immediately before or after, whip the egg whites in a stand mixer until soft. Turn the mixer down to low and slowly drizzle in the hot syrup and sprinkle on the xanthan sugar. Turn it up to medium-high and whip for a couple minutes until it's fluffy and pulls away from the sides in strings or ribbons (a bit like well-beaten ciabatta dough). Scoop the fluff into the prepared pan and attempt to spread into an evenly flat layer about an inch high. Dust the top with cornstarch, cover with plastic wrap, and put in the fridge to set.
After a few hours, prepare a tupperware by lining it with wax paper and dusting that with cornstarch. Put more cornstarch on a bowl or plate, and dredge a metal spatula and a pizza cutter in it. Use the pizza cutter to cut the marshmallows into 25 squares, then use the spatula to reinforce the cuts and lift the marshmallows out of the pan. Dredge the marshmallows in cornstarch and transfer them to the tupperware. Add more wax paper between the layers, and re-starch everything as necessary when things start sticking to other things.