Crab and salmon fishcakes with homemade tartare sauce

INGREDIENTS

• 250g/9oz small potatoespotatoes
• sea salt and freshly ground black pepper
• 2 tbsp olive oil
• 250g/9oz salmon
• 150g/5oz white crab
• 150g/5oz brown crab
• 1 tbsp good quality mayonnaise
• handful fresh flatleaf parsley
• handful fresh dill
• 1 red chilli
• 1 tsp Dijon mustard
• 1 tbsp olive oil
• 4 tbsp good quality mayonnaise
• 4 small cornichons or gherkins
• 1 tbsp capers
• ½ lemon
• 1 tsp grated fresh horseradish
• 2 large handfuls fresh baby spinach