Instructions
Follow the steps and taste along the way.
Cook the parsnip
Cut the parsnip into pieces approximately 2 cm in size. Put it in a pot with 1.2 l water, add 1 g salt, and simmer for 15–18 minutes, until the pieces can be easily pierced with a fork. Drain and reserve 100 ml of the cooking water.
Prepare the leek skillet
Cut the leek into thin rounds and the apple into small cubes. Heat 10 ml olive oil in a skillet, add the leek, and cook, stirring occasionally, for 4 minutes until softened but not browned. Add the apple and 60 ml water, cover, and simmer for 5 minutes. Stir in the mustard and apple cider vinegar, add 1 g salt and half the black pepper. Uncover and cook for 1–2 minutes, until only a little liquid remains in the bottom of the pan.
Blend the purée
Blend the cooked parsnip with 10 ml olive oil and 60 ml of the reserved cooking water. If the purée is too thick, add the remaining reserved water a spoonful at a time. Season with 1 g salt and the remaining black pepper; the purée should be smooth and hold its shape on a spoon.
Sear the mackerel
Pat the fillets dry once more with a paper towel and sprinkle with the remaining 1 g salt. Heat a clean skillet over medium-high heat, to approximately 180 °C, and add 10 ml olive oil. Place the fillets skin-side down and press them with a spatula for 10 seconds so the skin makes even contact with the pan. Cook for 4–5 minutes, until the skin is golden and crisp, then turn and cook for another 1–2 minutes. The center of the thickest part should reach 63 °C.
Serve
Place a quarter of the parsnip purée on each plate, top with a fillet skin-side up, and divide the warm apple-leek skillet alongside. Serve immediately so the skin stays crisp.
