Heat the heavy cream in a small saucepan over medium heat until it just begins to simmer. Remove from heat, add the tea bags, cover, and let steep for 10 minutes. Squeeze the bags to extract flavor and discard them.

While the cream steeps, melt the dark chocolate in a heatproof bowl set over a pot of simmering water (double boiler) or in the microwave in 30-second bursts. Stir until completely smooth and let cool slightly.

Whisk the egg yolks into the slightly cooled melted chocolate one by one until well combined. Stir in the tea-infused cream and vanilla extract until smooth.

In a separate clean, dry bowl, beat the egg whites with an electric mixer until soft peaks form.

Gradually add the sugar to the egg whites and continue beating until stiff, glossy peaks form.

Gently fold one-third of the egg whites into the chocolate mixture to lighten it. Then, carefully fold in the remaining egg whites using a spatula until no white streaks remain, taking care not to deflate the mixture.

Divide the mousse into serving glasses or ramekins. Refrigerate for at least 2 hours to set.

Just before serving, sprinkle a pinch of flaky sea salt over each portion to enhance the chocolate intensity.