Adjust oven rack to lower-middle position and heat oven to 300 degrees F.
Combine 2 cups of the cream, the sugar, and salt in medium saucepan; with a paring knife, scrape seeds from vanilla bean into pan, submerge pod in cream, and bring mixture to a boil over medium heat, stirring occasionally to ensure that sugar dissolves. Take pan off heat and let steep 15 minutes to infuse flavors.
Meanwhile, place kitchen towel in bottom of large baking dish or roasting pan and arrange eight 4- to 5-ounce ramekins (or shallow fluted dishes) on towel. Bring kettle or large saucepan of water to boil over high heat.
After cream has steeped, stir in remaining 2 cups cream to cool down mixture. Whisk yolks in large bowl until broken up and combined. Whisk about 1 cup cream mixture into yolks until loosened and combined; repeat with another 1 cup cream. Add remaining cream and whisk until evenly colored and thoroughly combined. Strain through fine-mesh strainer into 2-quart measuring cup or pitcher (or clean medium bowl); discard solids in strainer. Pour or ladle mixture into ramekins, dividing it evenly among them.
Carefully place baking dish with ramekins on oven rack; pour boiling water into dish, taking care not to splash water into ramekins, until water reaches two-thirds height of ramekins. Bake until centers of custards are just barely set and are no longer sloshy and digital instant-read thermometer inserted in centers registers 170 to 175 degrees, 30 to 35 minutes (25 to 30 minutes for shallow fluted dishes). Begin checking temperature about 5 minutes before recommended time.
Transfer ramekins to wire rack; cool to room temperature, about 2 hours. Set ramekins on rimmed baking sheet, cover tightly with plastic wrap, and refrigerate until cold, at least 4 hours or up to 4 days.
Uncover ramekins; if condensation has collected on custards, place paper towel on surface to soak up moisture. Sprinkle each with about 1 teaspoon turbinado sugar (1½ teaspoons for shallow fluted dishes); tilt and tap ramekin for even coverage. Ignite kitchen torch and caramelize sugar. Refrigerate ramekins, uncovered, to re-chill, 30 to 45 minutes (but no longer); serve.