Preheat the oven to 180°C/160°C fan/Gas 4. Grease a 1kg loaf tin with a little sunflower oil and line the base with baking parchment.
Coarsely grate the courgettes onto a clean tea towel, then gather the tea towel up and hold it over the sink. Twist it until all the excess liquid comes out of the courgettes.
Put the sunflower oil, sugar and eggs into a large mixing bowl and beat together until smooth.
Stir in the grated courgettes, the flour, baking powder and lime zest, mixing well. Stir in the lime juice and pistachios and mix once more. Transfer to the prepared tin, smoothing to level the surface.
Bake for 45 minutes until risen and light golden brown. Insert a skewer or sharp knife into the centre of the cake – if it comes out clean, the cake is ready; if not, return to the oven and bake for another five minutes, then check again.
Remove from the oven and leave the cake to cool in the tin for at least 10 minutes, before turning out on to a wire rack to cool completely.
Cut into slices to serve. Store any leftovers in an airtight container and eat within three days.
125ml sunflower oil
75g white sugar with stevia
250g self-raising wholemeal flour
½ tsp baking powder
finely grated zest of one lime
Juice of one lime
120g (shelled) pistachio nuts
Extracted from Eat Well for Less: Every Day, BBC Books, £14.99.