Heat the oven to 180C/160C fan/gas 4. Put the sweet potatoes on a baking tray and roast for 1 hr until tender when pressed. Leave until cool enough to handle (around 20 mins), halve, then scoop out the flesh into a mixing bowl, discarding the skins.
Add the miso, ginger, chilli, garlic, cumin, lemon juice and coriander to the bowl and mash with a fork. Season well. Fold in the fish.
Mould into eight fishcakes (about 100g each) and put in the fridge to chill for around 15 mins to firm up.
Mix the smoked paprika with the breadcrumbs and some seasoning on a plate. Put the flour and egg in separate shallow bowls. Dip the fishcakes in the flour, egg, and finally the breadcrumbs to coat. Transfer to a baking sheet lined with baking parchment, drizzle with 1 tbsp oil and cook for 30-35 mins until cooked through and golden.
Meanwhile, blanch the broccoli in boiling salted water for 1-2 mins, then drain and leave to steam-dry. Heat a griddle pan to high, toss the broccoli in 1 tsp oil, then griddle for 2-4 mins until tender. Whisk the soy and honey in a bowl, then toss through the broccoli. Serve with the fishcakes and a wedge of lemon, if you like.