Line a 9x13 inch pan with parchment paper and put about 1/8 cup cornstarch down so the marshmallows don't stick.
In a large mixing bowl or bowl of a stand mixer, sprinkle the gelatin over 1/2 cup of cold water. Let sit for 10 minutes to allow the gelatin to soften.
In a small saucepan, combine the honey, salt, 1/2 cup of the cold water, and marshmallow root powder over medium heat.
Cook over low heat, stirring constantly, for 5-7 minutes until the mixture is about 230°-240°F (use candy thermometer). Remove from heat and set aside.
Whisk the gelatin at a low speed for a few seconds to evenly distribute.
Slowly pour the honey mixture into the bowl with the softened gelatin.
Using an electric mixer, come to high speed slowly to avoid a hot honey splatter. Beat on high speed for about 10 minutes until the mixture has thickened and become white and fluffy.
Stir in the dried lavender and vanilla extract.
Pour the mixture into the prepared pan and smooth the top with a spatula.
Cover with remaining cornstarch and a sheet of parchment paper.
Let the marshmallows set overnight.
The next day, turn the marshmallows out onto a cutting board.
Using a sharp knife or pizza cutter dusted with cornstarch, cut the marshmallows into desired shapes.
Sprinkle with the dried herbs for added decoration.
Enjoy your homemade lavender marshmallows with marshmallow root!
Notes
Don't use lavender essential oil to replace lavender (don't ingest essential oils). Good alternatives are vanilla, strawberry, or cacao powder.