Directions

1. Bring a medium-sized saucepan of water to the boil and add the small potatoes. Bring the water back to the boil, then reduce the heat to low and cook the potatoes for 15-18 minutes, or until they are tender

2. Meanwhile, melt the butter in a frying pan over a medium heat. Score the skin of the mackerel into a criss-cross pattern and season the flesh side of the fillets. Add the mackerel to the pan, skin-side down, and cook the fish for 2-3 minutes or until the skin starts to crisp, then turn the fillets over and cook for a further 1-2 minutes, or until the fish is cooked. Remove the fillets from the pan and add the lime zest and juice, capers and spring onions and cook over a low heat for 1-2 minutes. Season to taste

3. Drain the potatoes well and then return them to the pan and use a spoon to crush them against the side of the pan until they split open
4. Spoon the potatoes onto a serving plate and place the fish fillets on top. Pour over the lime and caper sauce, so that any juices will be absorbed into the potatoes, and serve immediately.