To make the vinaigrette, whisk the white wine vinegar and olive oil together with some seasoning, then set aside. Boil a pan of water, add the broad beans and boil for 2-3 mins. Drain and plunge into iced water, then leave to cool a little before removing the skins.
Cut the baby courgettes into 4-5 pieces on the diagonal. If you are using medium courgettes, cut into four lengthways and slice into 5mm thick pieces.
Heat the olive oil in a frying pan over a medium heat, add the courgettes. Cook, stirring for 5-8 mins, until they are a light golden colour. Add the broad beans and some seasoning, and cook for another 30 secs. Remove from the heat and stir in the vinaigrette while still warm. Serve with the chopped walnuts scattered over.