Spicy tuna rice bowl with pickled beetroot

For the spicy tuna:

400g tuna

3 tbsp mayonnaise

2 tbsp crème fraîche

1 tbsp hot sauce

Juice 1 lemon

2 tsp sesame oil

Sesame seeds

2 scallions, finely sliced

For the pickled beetroot:

500g fresh beetroot

250ml apple cider vinegar

100g caster sugar

150ml water

½ tsp coriander seeds

½ tsp black pepper

1 bay leaf

For the rice:

375g sushi rice

450ml cold water, plus more for washing

1.5 tsp fine salt

1 tbsp caster sugar

40ml rice wine vinegar

1 small piece of kombu