Oil and 'flour' an 8 x 8 baking dish. Use arrowroot or ground coconut sugar for the 'flour'. If you're not paleo, you can use any all-purpose (GF or not GF) flour you'd like.
Pour the cold water into the bowl of a standing mixer or a bowl that you can use a hand mixer with.
Sprinkle the gelatin over the top and let stand while you prepare the honey syrup.
In a medium saucepan (mine holds about nine cups), gently heat the 3/4 cup of water.
Stir in the honey and salt just until combined.
Bring the mix to a low simmer (you should see bubbles forming, but not rising up). DO NOT STIR THE MIXTURE AT ANY TIME WHILE IT IS SIMMERING.
Allow the mix to reduce for about 12-15 minutes until it reaches the 'soft ball' stage (see Recipe Notes for link to a short video).
Along the way, the mixture may begin to rise as it reduces. If this occurs, just gradually reduce the heat and blow on it until it lowers back down.
Once it reaches the 'soft ball' stage or a temperature of 235-245℉, turn your mixer on low and begin adding the syrup SLOWLY to the gelatin/water mix.
Once all the syrup is added and incorporated, turn the mixer up to medium high and allow it to run for about 7-9 minutes until the marshmallow is fluffy and thick. It will almost be stiff-looking.
During the last minute of the mixer running, add in the stevia and vanilla.
Use a spatula to scrape the marshmallow into the 8 x 8 dish and spread it to fit. I like to use an oiled spatula so that the mix doesn't stick.
Set in the fridge until marshmallow is set (you should be able to lift the entire square out of the dish). This takes about an hour.
Use an oiled pizza cutter or knife to slice the whole square into as many marshmallows as you like (usually about 36 big ones or 288 small ones).