Add the self-raising flour and Greek yogurt to a mixing bowl with a good pinch of salt. Stir well then mix with your hands until it comes together into a dough.
Tip out onto a floured surface and knead for 1-2 minutes until smooth.
Roll the mixture into 12 small balls of dough (about 38g each); cover.
Mix the sugar and cinnamon on a plate; set aside.
Pour the vegetable oil into a wide saucepan (no more than half-full) and heat to 160°C.
Fry the doughnuts in two batches for 4 minutes, turning, until cooked through and an even golden brown.
Remove with a slotted spoon and drain on kitchen paper.
Roll in the cinnamon sugar while warm.
Leave to cool and then serve with salted caramel sauce.
