Preheat your oven to 180C. Place the Beetroot and Celeriac in a baking tray, with a tablespoon of water and cover tightly with tinfoil. Bake for 40mins, or until a fork can be inserted into them easily.
Peel, and leave to cool, before grating both into a medium sized bowl.
Place the Mackerel fillets onto a lined baking sheet, skin side up. Pop them under a medium grill for approximately 3 mins, or until the skin starts to crisp. Turn the fillets and place back under the grill until cooked through.
In a small frying pan, on a high heat, fry the capers until dark & crispy (about 3 mins).
Stir the grated Beetroot and Celeriac together with the wholegrain Mustard and the Mayonnaise.
Spoon the pink Remoulade onto two plates and top with the Mackerel fillets, garnish with parsley and a squeeze of lemon to taste
