Preheat oven to 325°F (165°C). Place four 6-ounce ramekins in a deep baking dish and set aside.

Heat the heavy cream in a medium saucepan over medium heat until it just begins to steam and tiny bubbles form around the edges, about 4 minutes. Remove from heat, add the tea bags, cover, and steep for exactly 10 minutes.

While tea steeps, whisk together the egg yolks, 1/3 cup sugar, vanilla extract, and salt in a medium bowl until smooth and pale yellow, about 1 minute.

Remove and squeeze the tea bags to extract maximum flavor, then discard. Slowly pour about 1/2 cup of the warm cream into the egg mixture while whisking constantly to temper the eggs. Gradually whisk in the remaining cream until fully combined.

Strain the custard through a fine-mesh sieve into a large measuring cup or bowl to remove any cooked egg bits. Divide evenly among the ramekins.

Carefully pour hot water into the baking dish until it reaches halfway up the sides of the ramekins. Bake for 35-40 minutes, until custards are set around the edges but still jiggle slightly in the center when gently shaken.

Remove ramekins from the water bath and let cool to room temperature, about 1 hour. Cover each with plastic wrap and refrigerate for at least 4 hours or up to 3 days.

Just before serving, blot any condensation from the custard surfaces with a paper towel. Sprinkle 1-2 teaspoons of granulated sugar evenly over each custard. Using a kitchen torch, caramelize the sugar by moving the flame in circular motions until golden brown and bubbling. Let stand for 2 minutes to harden before serving.