Directions
Step 1
Make the curd: Zest the lemons with a microplane grater, and then juice them—you should have 1 or more tablespoons of zest and 1 cup of juice. Some pulp is fine to include in the juice, but remove any seeds.
Step 2
In a saucepan, whisk the eggs and yolk thoroughly, and then whisk in, one ingredient at a time, the sugar, cornstarch, lemon juice and zest, vinegar, vanilla, and salt. Place the pan over medium heat and whisk constantly as it comes to a very low boil. Cook for 2 minutes, lowering the heat if necessary to prevent a rapid boil. The curd should be thick enough to coat the whisk.
Step 3
Remove from the heat. (If you see bits of egg white, use the blade of a spatula to press the curd through a fine strainer into a bowl.) Slowly whisk in the olive oil until completely blended. Pour the curd into a glass bowl or jar and allow it to come to room temperature before covering with plastic wrap and placing in the fridge to thicken further, about an hour.
Step 4
Make the blueberry compote: Mix 3 cups blueberries, cornstarch, sugar, water, vinegar, and salt in a frying pan (this allows for more even cooking than a saucepan). Bring to a boil, stirring frequently. Turn the heat down to a simmer and cook, stirring occasionally, until most of the blueberries break up and the mixture thickens, about 3 to 5 minutes. While still warm (but not hot), fold in the olive oil and the last cup of berries. Let it come to room temperature before serving (refrigerate if not using within an hour).
Step 5
Make the mousse: Whip the cream and sugar until stiff. Gently fold in the lemon curd with a large spatula until mostly combined. Chill until ready to serve.
Step 6
To serve, spoon ample amounts of mousse into dessert bowls or glasses. Stir the compote, then place dollops randomly around the mousse. If desired, use a microplane grater to top each serving with lemon zest.
