Mix the celeriac and cornflour, spread on a baking tray lined with baking paper, add the oil and thyme, mix and season.
Approx. 45 mins. in the centre of an oven preheated to 220°C.
Fry the bacon in a non-stick frying pan until crispy, without adding any oil. Add the vinegar, oil and single cream, season. Add the spinach and thyme, briefly bring to the boil.
Rinse the fish in cold water, pat dry, season. Heat the oil in a non-stick frying pan. Fry the fish for approx. 3 mins. on each side. Plate up the celeriac, top with the sauce, fish and spinach.