Start by greasing a 9x9” baking pan with avocado oil. Dust all sides lightly with powdered sugar.
In the bowl of a stand mixer, add water and mix with powdered gelatin until combined. Let sit.
In a medium-sized pot, add granulated sugar, corn salt, and water. Mix to combine.
Set over medium-high heat and bring to a light boil. TIP: Watch the sugar mixture and stir every few minutes during this process! You do not want the sugar to burn. Usually, this stage takes 5-10 minutes in total. Boil until 240F and immediately remove from heat.
In a stand mixer with the whisk attachment, whisk the gelatin a bit on low speed before slowly streaming the syrup mixture down the side of the bowl. Gradually increase speed until high.
Once on high speed continue streaming in the syrup until all is added. Keep whisking for 5 minutes.
Before removing from the stand mixer, beat in vanilla extract until combined. The mixture should be fluffy, white, and up to 3x more volume than the initial mixture.
Immediately remove from the stand mixer and immediately pour into the dusted baking dish. Even out using a silicone spatula or hands
Leave on the counter uncovered for 12 hours.
Turn the set marshmallow out onto a work surface dusted with powdered sugar. Cut the marshmallows with an oiled knife.
Sprinkle cut pieces with more powdered sugar before serving or storing them in an air-tight container.
STORAGE: Do NOT store them in the refrigerator as they will melt. Store in an airtight container at room temperature. Marshmallows store well for 2-3 weeks on the counter.