Green chicken salad

Ingredients

• 1
  small red onion , finely chopped
• 1
  lemon , juiced
• 1
  small rotisserie chicken , around 250g meat, picked and shredded
• 4
  sticks celery , finely chopped
• 4
  spring onions , finely sliced
• ½
  large cucumber , deseeded and finely chopped
• 6
  cornichons , roughly chopped
• 1
  green pepper , deseeded and cut into 1/2cm cubes
• large handful of soft herbs (we used dill and parsley), roughly chopped
• toasted sourdough , to serve
• 50
  g natural yogurt
• 2
  tsp Dijon mustard
• 50
  g mayonnaise
• 50
  ml olive oil