Make the Strawberry Puree : In a medium saucepan, combine the strawberries, orange liqueur, orange juice, granulated sugar, and strawberry preserves. Cook over medium heat for 5–7 minutes, stirring occasionally, until the strawberries release their juices and soften. Remove from heat and let the mixture cool slightly. Blend it into a smooth puree using a blender or immersion blender. Set aside to cool completely.

Prepare the Mascarpone Cream : In a heatproof bowl, whisk together the egg yolks and granulated sugar. Place the bowl over a pot of simmering water (double boiler method), whisking constantly, for about 5 minutes or until the mixture thickens and is pale yellow. Remove from heat and let it cool. In a separate bowl, whip the heavy cream until stiff peaks form. In another large bowl, beat the mascarpone cheese until smooth. Add the cooled egg yolk mixture, orange zest, and vanilla extract, mixing until fully combined. Gently fold the whipped cream into the mascarpone mixture until smooth and fluffy.

Assemble the Tiramisu : Spread a thin layer of the mascarpone cream on the bottom of a 9x13-inch dish (or a similar-sized dish). Dip each ladyfinger briefly into the strawberry puree, ensuring they are soaked but not soggy, and arrange them in a single layer over the mascarpone cream. Spread half of the mascarpone cream over the ladyfingers. Top with a layer of sliced strawberries. Repeat the layers with the remaining ladyfingers, mascarpone cream, and sliced strawberries.

Chill and Serve : Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight, to allow the flavors to meld and the tiramisu to set. Before serving, garnish with additional fresh strawberries or a dusting of powdered sugar if desired.