Preheat the oven to 200°C.
Heat a frying pan and add 15ml of olive oil.
Season hake fillets and fry skin-side down for one minute.
Transfer fish to a baking tray.
Bake hake for four minutes, then remove to rest.
De-shell shrimps and set meat aside, reserving the shells.
Sauté shallot and leek in 15ml of oil for one minute.
Add garlic and sauté for one additional minute.
Add tomato purée and shrimp shells and cook for four minutes.
Deglaze with brandy, add fish stock, and simmer for four minutes.
Stir in cream and season to taste.
Cool slightly and blend in a food processor until smooth.
Strain the sauce through a fine sieve into a clean saucepan.
Simmer the sauce and add the reserved shrimp meat.
Boil potatoes in salted water until tender and drain.
Crush potatoes with a fork and season well.
Mix potatoes with crab, tomato, spring onion, half the lemon juice, oil, and dill.
Serve hake atop potatoes, drizzle with remaining lemon and oil, and spoon sauce around.