Place the parsnips on a small baking tray and roast for 30-35 minutes, until cooked through and soft. Once cool enough to handle,. place the flesh in a large bowl (you should have around 270-300g cooked parsnip) roughly mash and set aside to cool. Alternatively, you can mash in a blender.
Place the fish in a food processor and pulse a few times (you want it roughly chopped rather than minced) then add to the parsnip, with a half-teaspoon of salt, plenty of pepper and the remaining ingredients (dill, chives, garlic, lemon zest, egg, and anchovy fillets) apart from the oil.
Mix well and form into 6- 8 patties: they should be about 8cm wide and 2-3cm thick. At this stage, you could cover the patties and refrigerate until ready to cook, up to 24 hours ahead of time.
Remove the fishcakes from the fish and dip both sides into sesame seeds.
Place on an oiled baking tray and roast in the oven for 25-30 mins until golden brown.
Serve with horseradish cream or sour cream.
This recipe was inspired by Yotam Ottolenghi