Cod & spinach yellow curry

Name: Cod & spinach yellow curry
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: Thai
Ingredients: 1 tsp garam masala; 1 tsp turmeric; 1 tsp smoked paprika; 250g cod fillet, cut into bite-sized chunks; 2 tbsp groundnut oil (or any flavourless oil); 1 onion , finely sliced; 2 garlic cloves , finely sliced; thumb-sized piece ginger , grated; 400g can coconut milk; 100g fresh spinach; cooked basmati rice and naan bread, to serve (optional)