2 green apples, cored and cut into wedges
2 red apples, cored and cut into wedges
陆 head celery with leaves, sliced
1 lemon, juice only
2 tsp Dijon mustard
1 tbsp Dijon mustard
3 tbsp cracked black pepper
3 tbsp olive oil
110g/4oz walnut halves
4 fillets fresh mackerel, pin-boned