Preheat the oven to 180°C and lightly grease a loaf tin, or line it with baking paper.
Coarsely grate the beetroot and carrots.
In a large bowl, combine the grated beetroot and carrot with the mashed banana, eggs, oil, and sugar.
Using a hand-held blender or mixer, blend the mixture briefly until you have a coarse purée.
In a separate bowl, mix together the flour, baking powder, oats, and cinnamon.
Add the dry ingredients to the wet mixture and stir to combine. Adjust the texture if needed — the batter should be thick but pourable. Add a little more flour or oats if it feels too loose.
Fold in the raisins or sultanas.
Spoon the batter into the prepared loaf tin, or divide between two small silicone loaf tins.
Bake in the oven for 30–45 minutes, until set and a skewer inserted into the centre comes out clean.
For smaller loaves in an air fryer, bake at 180°C for 20–25 minutes.
Leave to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely, before slicing it.