First, sprinkle the gelatin powder over the water in a small bowl and mix it in. Scrape down any gelatin stuck to the sides of the bowl, then let it sit for 5 minutes.
Next, put the quartered strawberries, sugar, and freeze-dried strawberries into a blender or food processor. Blend them until they're smooth. Pour this mixture into a medium-sized bowl and set aside.
Now, take a large bowl and pour in the heavy whipping cream. Whip it on medium-high speed until it becomes thick and forms stiff peaks. This should take about 5 minutes.
Take the small bowl with the gelatin mixture and heat it in the microwave for 10 seconds to ensure the gelatin fully dissolves. Then pour it into the bowl with the strawberry mixture. Stir everything together until it's fully mixed.
Carefully fold the whipped cream into the strawberry mixture until there are no more white streaks left.
Put the mousse into the fridge to chill for at least 30 minutes, or you can leave it in overnight if you want. Time to enjoy!