Hake with crushed baby potatoes, buttered spinach and a saffron vinaigrette

Ingredients

• 2 Fishbox hake fillets, with skin on (optional)
• 300g of washed baby potatoes
• 2 handfuls of washed baby spinach
• 1 tbsp of extra virgin olive oil
• 20g unsalted butter
• Sea salt and freshly ground black pepper
• A pinch of saffron
• 1 tbsp of white wine vinegar
• 1 tsp (heaped) of Dijon mustard
• 4 tbsp of extra virgin olive oil