1
Preheat the oven to 200°C/180°C fan/400°F/Gas 6.
2
Put the potatoes into a large pan with the salt and cover with water. Bring to the boil then simmer gently, uncovered, stirring occasionally until the potatoes are cooked and covered in a thin layer of salt and all the water has evaporated, taking about 30–35 minutes.
3
Meanwhile, put the fish into an ovenproof dish and scatter the tomatoes and garlic around it. Dot with the butter, drizzle with 1 tbsp of the olive oil and season well. Roast in the oven for 20–25 minutes until the fish is just cooked.
4
Wilt the greens in a covered pan with a little oil over a high heat. Add a splash of water and cook until tender. Remove the greens from the pan.
5
To make the brown butter, add the butter to the frying pan until it foams and smells nutty, then whisk in the lemon juice, capers and vinegar.
6
Drizzle the brown butter on the fish, then scatter with the flaked almonds and serve with the potatoes and greens.