01 - Rinse and hull the strawberries, then cut them in half. Arrange them evenly in a rectangular mold or loaf pan approximately 8 x 4 inches.
02 - In a small saucepan, combine the milk, sugar, and agar-agar. Whisk well to dissolve the agar-agar completely.
03 - Place the saucepan over medium heat. Bring the mixture to a gentle simmer, stirring constantly. Continue to simmer for 2 minutes to fully activate the agar-agar.
04 - Remove from heat and stir in the vanilla extract.
05 - Allow the milk mixture to cool for 2-3 minutes, then gently pour it over the strawberries in the mold. Tap the mold lightly to remove any air bubbles and ensure the strawberries are evenly distributed.
06 - Let the yokan cool to room temperature, then refrigerate for at least 3 hours, or until fully set.
07 - Once set, unmold onto a cutting board and slice into portions. Garnish with mint leaves if desired.