Prepare an herbal “tea” by bringing one cup of water to a simmer, remove from heat, add dried herbs and cool.
When the elderflower “tea” is cool, strain and place 1/2 cup of the tea in the bowl of a stand mixer. Added the gelatin, mix and allow to “bloom”. Fit mixer with the whisk attachment.
Add the remaining 1/2 cup of herbal tea to a medium saucepan with high sides. Add sugar and light corn syrup. Over medium high heat and stirring constantly, boil the sugar syrup until it reaches soft ball stage, 240 degrees (F) on a candy thermometer. Remove from heat.
Immediately turn on the mixer to low speed and slowly pour the hot syrup into the gelatin mixture. When done pouring, increase the speed to high.
Continue whisking until the mixture is white, light, airy, and at least doubled in volume. For rose marshmallows, add rose water now and mix well to combine.
Prepare a non-metal 9×13 inch baking dish by lightly greasing the bottom and sides and then dusting the surface with a small amount of the powdered mixture to coat. Pour marshmallow mixture into prepared dish, smooth with a spatula, and dust the top with more powdered sugar.
Allow to dry in a dish for 12 hours or overnight. Using a knife dipped in hot water, cut through marshmallows to desired serving size. Toss individual marshmallows in more powdered sugar to coat.