Mix together the yogurt, peanut butter and vinegar in a bowl
Sift in the flour, baking powder and bicarbonate of soda
Add the milk and carefully fold in – don’t mix it too much
Divide half of the mixture into a greased muffin tin
Place 1 teaspoon of strawberry jam into the centre of the batter
Cover them all with the remaining half of the batter
Bake in oven for 15 minutes, until risen and a skewer inserted into the side of a donut comes out clean (be careful to insert it into the side not the middle as you don't want any jam leaking out!)
For the glaze:
Mixing the peanut butter and icing sugar in a bowl with a splash of hot water (keep adding water until you think the icing has reached the right consistency – thin enough to be spread easily over the donuts but not so thin that it’ll drip down the sides)
Once out of the oven, remove the donuts from the baking tin, place on a wire rack and spread the glaze over the top