Wash the strawberries, remove the tops then chop them in half. Add them to a blender and blend to a puree. Pour the blended strawberries into a saucepan and place the pan on a medium heat. When the strawberries begin to bubble give them a stir and continue to stir occasionally. After a while, you will notice a lighter colour liquid on top of the strawberries, when that lighter liquid disappears then you know the reduction is complete. Remove the strawberry reduction from the heat and pour into a small bowl to cool.
Preheat the oven to gas mark 4/350oF/180oC/160oC fan and line a 12-count muffin tin with 12 cupcake cases. To a medium sized bowl, add and combine the flour, salt and bicarbonate soda then set aside.
To a mixing bowl, add the baking spread and sugar then cream them together until light and fluffy. Mix in the eggs and vanilla extract then mix in the soured cream and milk. If using pink food colouring then add it in at this stage.
From the bowl with the reduced strawberries, remove 2 tablespoons of the reduced strawberries, add to a separate container and refrigerate. This will be used for the glaze. Pour the rest of the reduced strawberries into the batter and combine.
Gradually add in the dry ingredients set aside earlier and mix until well combined. Spoon the batter evenly between the cupcake cases and bake the cupcakes for 20 minutes. Remove from the oven and place the baking tin on a cooking rack for 15 minutes then transfer the cupcakes to a cooling rack to completely cool.
Once the cupcakes have cooled, make the glaze by combining the icing sugar with the reduced strawberries that you place in the fridge earlier. Continue to mix until smooth. If you want to loosen the mixture then add the milk. Using a butter knife or palette knife, spread 1 teaspoon of the glaze onto each cupcake then add sprinkle if using.