Hake with harissa, fennel and capers

2 big fillets of Irish hake

2 tbsp olive oil

1 fennel bulb

1 medium onion

2 cloves of garlic, minced

1 heaped tsp harissa paste

1 heaped tbsp capers

sea salt and freshly cracked black pepper

1 lemon

Small handful of parsley leaves, chopped