01 - Rinse strawberries, remove green hulls, and cut each berry in half. Arrange strawberry halves evenly in a rectangular mold or loaf pan (approximately 8 x 4 inches).
02 - In a small saucepan, combine whole milk, granulated sugar, and powdered agar-agar. Whisk thoroughly until agar-agar is completely dissolved and no lumps remain.
03 - Place saucepan over medium heat. Bring mixture to a gentle simmer while stirring constantly. Maintain simmer for 2 minutes to fully activate gelling properties of agar-agar.
04 - Remove saucepan from heat source. Stir in vanilla extract until fully incorporated into warm milk mixture.
05 - Allow mixture to cool briefly for 2-3 minutes. Gently pour over arranged strawberries in mold. Lightly tap mold on counter to release air bubbles and distribute strawberries evenly.
06 - Let yokan cool to room temperature, then refrigerate for minimum 3 hours or until completely set and firm to touch.
07 - Once fully set, unmold onto cutting board and slice into rectangular portions. Garnish with fresh mint leaves if desired before serving.