Warm the oat milk, plant block and vanilla together in a small pan until the plant block has melted down, but the mixture is not too hot. Stir the yeast, the 3 tbsp of sugar, the flour and salt together in a large bowl. Make a well in the middle and pour in the warm oat milk mixture. Combine using a wooden spoon, then tip out onto a lightly floured surface and knead for 10 mins until smooth and elastic. Transfer to a clean, lightly oiled bowl, cover and leave to prove for 1-2 hrs until doubled in size.

Tip the proved dough out onto a work surface to knock it back (this removes some of the air that has built up). Divide into 10 equal pieces and roll into smooth balls between your palms. Arrange on a baking tray lined with baking parchment, leaving plenty of space between them, then cover and leave to prove for another 30 mins-1 hr until doubled in size again.

Fill a large saucepan no more than two-thirds full with oil and heat to 180C, or until a cube of bread dropped in browns within 30 seconds. Use a small 1cm round stamp-style cutter to remove the middle of each dough ball (reserve these for frying at the end). Meanwhile, put the remaining 50g sugar in a shallow bowl.

Fry the ring doughnuts in batches for 30 seconds on each side until cooked through and golden. Transfer to a plate lined with kitchen paper to drain slightly, then toss in the sugar to coat. Repeat with the reserved doughnut middles, then serve all the doughnuts warm.