For all the lemon lovers, this mousse is a dream come true. It’s smooth, fluffy, and perfectly balanced between sweet and tart, with a texture that practically melts in your mouth.
Pour the water into a small bowl. Sprinkle the gelatin in an even layer over the cream and set it aside to bloom.
Set a saucepan filled with 1-2 inches of water on the stove over medium heat. Bring it to a simmer and maintain it.
Place egg yolks, sugar, lemon juice, lemon zest, and salt in a heatproof bowl that sits on top of the saucepan, but doesn’t touch the water. Whisk until combined, then continue whisking as the curd cooks, bubbling and thickening and coating the back of a spoon, about 10 minutes.
Meanwhile, heat the bloomed gelatin in the microwave in 10 second increments until it's melted and hot to the touch. Add a few drops of food coloring (if using).
Remove the saucepan from the heat and stir the hot gelatin until well combined.
Press a piece of plastic wrap onto the surface of the curd and chill in the refrigerator for at least 2-3 hours, until completely cooled.
When ready to finish, use an electric mixer with the whisk attachment to whip the heavy cream until medium peaks form.
Remove the curd from the refrigerator. Working in 3 batches, use a rubber spatula to gently fold the whipped cream into the custard, incorporating each batch fully before adding another, and trying not to deflate the whipped cream.
Divide the mousse into individual serving bowls, then refrigerate for at least 30 minutes, or until the mousse is set. Serve with whipped cream and fresh berries, if desired.