In a large, heavy-bottom pot, mix the strawberries, sugar, lemon juice, cardamom pods, and vanilla bean. Stir over medium-low heat until the sugar is dissolved.
Increase heat to medium-high and bring mixture to a rolling boil.
Stir frequently, mashing the strawberries as you stir. Continue to boil until jam is thickened and bubbles completely cover the surface of the jam (about 10 minutes); the jam should reach 220°F.To check if your jam is done, use the wrinkle test. Before cooking the jam, put 3 or 4 small heatproof plates in the freezer. Once your jam has boiled for several minutes, take the pan off the heat and carefully spoon a little jam onto one of the cold plates. Let it stand for a minute then push the blob of jam with your finger, if the surface of the jam wrinkles then it has set, if it is still quite liquidy then put the pan back on the heat and boil the jam for another 3 to 5 minutes before testing again on the next plate.
Once jam has set, remove the vanilla bean and cardamom pods, and spoon the jam into clean jars. Cover and store in the refrigerator.
Preheat the oven to 350°F.
Take your thawed puff pastry, and cut each sheet into 6 rectangles. Evenly fill half of the rectangles with the chilled strawberry cardamom jam.
Lay the remaining 6 rectangles over the filling and seal the edges by crimping with the back of a fork. Repeat until you have 6 tarts.
Place on parchment-lined baking sheets and brush the tops of the tarts with water. Transfer to the oven and bake the tarts for 15 to 20 minutes or until puffed and deep golden brown. Let cool slightly.
Meanwhile, whisk together the milk, powdered sugar, and strawberry cardamom jam. If needed, add 1 tablespoon of milk or jam at a time to thin the glaze as desired. Drizzle the glaze over the pop tarts and allow to set at room temperature. Enjoy!
This jam isn’t “canned” or processed for long-term storage and should be kept refrigerated & consumed within two weeks.