Steps
1. Melt the dark chocolate in a heatproof bowl over simmering water, stirring until smooth.
2. Dissolve the instant coffee in the warm milk and add it to the melted chocolate, mixing well.
3. In a separate bowl, whisk the egg white with a pinch of salt until stiff peaks form.
4. Gently fold the egg white into the chocolate mixture until fully combined.
5. Spoon the mousse into a serving dish and refrigerate for at least 30 minutes to set.
6. Serve chilled, topped with sliced strawberries.