Place the water in a small bowl and sprinkle the gelatin on top.
Heat the milk in a small pot over low heat.
Whisk the egg yolks and sugar together in a medium bowl, until pale and doubled in volume.
When the milk is steaming, pour it into the yolk mixture in a slow, thin stream, while whisking.
When all the milk has been added, transfer the mixture back to the pot and cook over low heat, whisking, until slightly thickened (about 5 minutes).
Stir in the gelatin mixture, the fresh strawberries, strawberry preserves, lemon juice, and salt.
Cool the mixture to room temperature.
Whip the cream until it holds stiff peaks, then fold into the strawberry mixture. Tint with food coloring, if using.
Pour the mousse over the chocolate base, and refrigerate for 2 hours or until set.