Step 1Mix vanilla extract into hot Custard Ice Cream Base in bowl. Place in freezer to chill, stirring occasionally, about 1 hour.
Step 2When ice cream mixture is cool, place in ice cream maker and freeze according to manufacturer's instructions. Immediately line 2-quart mold or bowl with 3/4 to 1 inch ice cream, using spatula or spoon dipped in warm water if necessary, and place mold in freezer 2 to 24 hours.
Step 1Combine strawberries, 1 teaspoon sugar and lemon juice in bowl of food processor or blender and puree until smooth. Strain and set aside.
Step 2Mix water and 1 cup sugar in small, heavy saucepan and boil over medium-high heat until clear, 5 minutes. Remove from heat and let cool.
Step 3Stir egg yolks and strawberry puree into syrup. Return to medium heat and whisk until thickened, then remove from heat and beat until cool.
Step 4Whip cream until it forms stiff peaks, then fold into egg yolk-strawberry puree mixture. Fill interior of ice cream-lined mold with mixture, cover with plastic wrap and set in freezer until solid, 2 to 3 hours.
Step 1Remove plastic wrap and dip mold in hot water until bombe is loosened. Place serving plate upside down on top of mold; holding mold and plate together, overturn so that bombe drops onto plate.
Step 2Smooth surface with spatula and cover with blueberries. Return to freezer for 1/2 hour or more to firm up.