Smoked Mackerel Pâté with Pickled Beetroot

For the pâté

1 whole smoked mackerel or 2 smoked mackerel fillets

100g mayonnaise

60g crème fraiche

1 lemon, zest and juice

2 tbsp parsley, finely chopped

1 tbsp dill, finely chopped

½ tsp freshly ground black pepper

½ tsp sea salt

For the pickled beetroot

750g beetroot (or 3 large beetroots)

400ml apple cider vinegar

350g caster sugar

400ml water

1 tsp coriander seeds

1tsp black peppercorns

A pinch fine sea salt