Preheat the oven to 200Â°C. Hull the strawberries and place them in a large pyrex heatproof dish or a non-stick roasting tin.
Slice through the vanilla pods length-ways, and open the pods. With the back of a knife, remove the vanilla seeds, and mix the seeds into the caster sugar. Place the empty vanilla pods into a jar of sugar, and the aroma will scent the sugar, for cake baking.
Place the vanilla sugar in a separate pyrex dish or non-stick roasting tin. Place both the sugar and the strawberries, which are on separate dishes or tins, in the oven, and roast for 30 minutes. The strawberries will start to go soft, and the sugar will be hot. Remove from the oven.
Combine the hot sugar and the soft strawberries. The heat of the sugar will make the strawberries melt into a gooey, sweet jam. Cool the strawberry jam.
Fill the sterilized jam jars with the strawberry jam, and cover the jam with a small disc of grease-proof or wax paper. Then close the jars tightly, and label with the name of the jam and the date. You can store the jam in a cool, dark place, and it should keep for a good 6 months.
Serve the jam spooned over Greek yogurt in small serving bowls with a sprinkling of granola and chopped strawberries.