Ingredients
1 fennel bulb (around 250g) 
2 large oranges 
1 small red onion, thinly sliced (120g) 
120g rocket 
1 tsp cider vinegar 
1 tbsp flavourless oil 
1 tbsp wholegrain mustard 
Salt and pepper 

Equipment needed 
A mandolin

Method
Put your very thinly sliced onion into a large non-metallic bowl with the cider vinegar.  Stir so the onions all get coated.  This takes the raw sharpness out of the onion so you get all of the flavour without the unpleasant overpowering onion. 

Over the onion bowl peel and segment the oranges, doing this over the bowl catches any juice.  Very carefully holding the orange over the bowl cut each piece of orange out leaving behind the skin.  To do this, on each little segment or triangle, cut down the side of the skin both sides and it should pop out.  Put the orange pieces into the bowl with the onion.  When you have finished segmenting the orange, give the skin a big squeeze over your bowl to catch any remaining juice and discard the skin and pith. 

Slice the fennel and put into your bowl. 

Very carefully drain the orange/cider vinegar from the onions into a little cup or jug.  This might feel awkward but mellowing the onions is worth this fiddle.  Add the mustard to the orange vinegar and thoroughly whisk.  While whisking slowly add the oil. 

Put the rocket into the onion bowl and carefully toss together.  Dress your salad with your dressing and serve immediately. 

- Based on this recipe