Preheat oven to 300°.
Combine 1/3 cup sugar and the egg yolks in a medium bowl, stirring well with a whisk.
Combine the milk and crystallized ginger in a medium saucepan. Heat the milk mixture over medium heat to 180° or until tiny bubbles form around the edge (do not boil), stirring occasionally. Strain mixture through a sieve into a bowl, and discard the solids. Stir in the vanilla extract. Gradually add milk mixture to egg mixture, stirring constantly with a whisk.
Divide the mixture evenly among 6 (4-ounce) ramekins, custard cups, or shallow baking dishes. Place ramekins in a 13 x 9-inch baking pan; add hot water to pan to a depth of 1 inch.
Bake at 300° 45 minutes or until the center barely moves when ramekin is touched. Remove ramekins from pan, and cool completely on a wire rack. Cover ramekins and chill at least 4 hours or overnight.
Carefully sift 1 tablespoon sugar evenly over each custard. Holding a kitchen blow torch about 2 inches from the top of each custard, heat the sugar, moving the torch back and forth, until the sugar is completely melted and caramelized (about 1 minute). Serve the custards immediately or within 1 hour.
Note: Sugar topping can be prepared on the stovetop. Place 6 tablespoons sugar and 1 tablespoon water in a small, heavy saucepan. Cook, without stirring, over medium heat until golden (about 5 to 8 minutes). Immediately pour over cold custards, and quickly spread to form a thin layer.