Pre-heat the oven to 170° C and grease and line baking trays with parchment paper.
In a mixing bowl, cream the margarine and sugar until pale and fluffy using a handheld electric whisk. Beat in the flour, bicarbonate of soda and vanilla extract and knead this dough lightly for 5 minutes. Roll the dough out on a lightly floured surface to 1cm thickness and cut shapes using a 5 cm diameter star-shaped cutter.
Arrange on the baking trays spaced apart then use your thumb to make an indent in the centre of each cookie. Bake for 15-20 minutes and let them cool on the baking tray for a few minutes before moving to a wire rack to cool completely.
Once cool, spoon the strawberry jam into the indents in the centre of the cookies, and serve when ready.