Lemon butter baked white fish with shredded hispi cabbage

Name: Lemon butter baked white fish with shredded hispi cabbage
Ingredients: 2 fillets sustainable white fish; 1 lemon ½ thinly sliced and ½ cut into 2 wedges; 25g butter; 300g new potatoes halved; 1 tbsp olive oil; 1 red pepper deseeded and thinly sliced; 1 yellow pepper deseeded and thinly sliced; 1 carrot julienned or finely sliced; 2 garlic cloves finely grated or crushed; ½ tsp chilli flakes; a few thyme sprigs leaves picked; 250g hispi cabbage cored and finely sliced; chopped parsley to serve (optional)