Preheat oven to 325°F.
If using a vanilla bean, slice it open and scrape out the seeds. Put the seeds in a large bowl. Place the empty pod in a pot and combine with salt and heavy cream.
Heat the cream mixture on the stove until it simmers, without boiling (low heat for about 10 minutes). Remove from heat; discard the vanilla pod. Stir in vanilla extract or paste if you’re using those instead.
Meanwhile, in your bowl with vanilla seeds, add egg yolks and 1/2 cup sugar. Whisk (by hand) until combined. Simultaneously, bring 6 cups of water to a boil.
Do not whisk too briskly or you’ll end up with a custard that rises and falls or has lots of bubbles on the surface. While whisking at a slow and steady pace, gradually pour in 1/4 of the warmed cream mixture into the egg and sugar blend. Mix until combined, then continue to add remaining cream mixture, while whisking consistently.
Position ramekins in a 9×13-inch pan. Pour the custard mixture into the ramekins, filling almost to the top. Carefully (using a glass liquid measuring cup) scoop boiling water into the pan until it’s halfway up the sides of the ramekins.
Carefully transfer to oven and bake 30–35 minutes until the custards are set (with a slight jiggle in the center when you gently shake). Remove from water bath and allow to cool at room temperature, then chill in fridge for 6–8 hours (or up to 4–5 days).
When ready to serve, sprinkle remaining 1/4 cup sugar evenly over the custards. Swirl the sugar for even coverage, tipping excess into the next ramekin. Caramelize the sugar using a kitchen torch until it’s golden or slightly charred. Garnish with fresh berries and serve immediately.
Alternative Caramelization (no torch): Ensure brûlées are chilled for at least 24 hours. Adjust oven rack to topmost and set to high broil. Broil sugar-topped custards for 1–3 minutes, watching very closely. Then refrigerate for 10–20 minutes to re-firm custard.