You can make the strawberry puree by cooking fresh or frozen berries in a saucepan for about 10 minutes, then blending the soft berries in a blender or food processor. Note that marshmallows need to sit for at least 8-10 hours before cutting them, so it’s a good idea to make these the night before you plan to eat them.
- 1-1/4 cups water, divided
- 1/2 cup strawberry puree
- 4 envelopes gelatin
- 3 cups sugar
- 1-1/4 cups light corn syrup
- 1/3 cup powdered sugar
- 1/3 cup cornstarch
1. Prepare a 9x13 pan by lining it with aluminum foil and spraying the foil liberally with nonstick cooking spray.
2. Place ½ cup of the water and the strawberry puree in the bowl of a large stand mixer. Sprinkle the gelatin on top and stir briefly to distribute. Let gelatin sit and dissolve for at least 5 minutes.
3. Place remaining ¾ cup of water, corn syrup, and sugar in a medium saucepan over medium-high heat. Stir to dissolve the sugar, and insert a candy thermometer.
4. Allow the mixture to cook without stirring until it reaches 240 degrees on the thermometer. Brush down the sides occasionally with a wet pastry brush to avoid crystallization. While the candy cooks, briefly run the mixer on low to ensure the gelatin and puree is well-mixed.
5. Once the candy reaches the proper temperature, remove it from the heat immediately. Turn the mixer to low, and slowly pour the hot syrup into the mixer bowl. Be careful, as the syrup is extremely hot. If you have a large (at least 3 cup) liquid measuring cup with a spout, you can transfer the hot syrup to the cup before pouring to make it easier.
6. Gradually increase the speed of the mixer until it running on high. Whip the marshmallow mixture for 10 minutes, or until it is stiff and shiny. You can tell it is done when you stop the mixer and lift up the beater, the marshmallow will slowly drip back down into the bowl in a thick, shiny stream.
7. Pour the marshmallow into the prepared pan and smooth the top. Allow it to sit and firm up at room temperature for at least 10 hours.
8. Sift the powdered sugar and cornstarch together. Cover your workstation with waxed paper to protect it, and liberally sprinkle the surface with the sugar/starch mixture. Sprinkle the top of the marshmallow with the sugar/starch coating, and flip the marshmallow face down onto the prepared surface.
9. Carefully peel back the foil from the marshmallow, and sprinkle the top of the marshmallow slab with the coating powder. Spray a large smooth-bladed knife with nonstick cooking spray, and coat both sides with the coating powder. Cut the marshmallow into squares, coating the knife blade with sugar/starch as needed. Roll the cut edges of the marshmallows in the coating mixture so that all sides are smooth and not sticky.
10. To save marshmallows, store them in a dry airtight container in a temperate, dry location. Do not refrigerate them or keep them in a very humid place. If they are stored longer than two or three days, you may need to re-roll them in coating. Fresh marshmallows go stale after about a week, so these are best eaten soon after they are made.