Prepare the Strawberry Sauce
In a small bowl, whisk together the strawberry jam, water, and lemon juice until smooth.
Make the Mascarpone Filling
In a medium mixing bowl, combine the mascarpone cheese, heavy cream, sugar, vanilla extract, and lemon zest.
Beat with an electric mixer for about 2 minutes, or until the mixture becomes thick, fluffy, and holds soft peaks.
Assemble the First Layer
Quickly dip each ladyfinger into the strawberry sauce, coating both sides without soaking them for too long.
Arrange 12 dipped ladyfingers in a single layer in an 8×8-inch baking dish.
Spread half of the mascarpone filling evenly over the ladyfingers.
Top with half of the sliced strawberries.
Assemble the Second Layer
Repeat with the remaining dipped ladyfingers.
Spread the remaining mascarpone filling over the second layer.
Arrange the remaining strawberries on top.
Chill
Cover the dish tightly with plastic wrap.
Refrigerate the No-Bake Strawberry Tiramisu for at least 8 hours, or overnight, to allow the layers to soften and the flavors to blend.
Slice and serve chilled.