Spiced salmon and sprout traybake

Name: Spiced salmon and sprout traybake
Prep time: 15 min
Total time: 15 min
Ingredients: 1 large red onion, sliced; 3 garlic cloves, sliced; 1 tbsp mustard seeds; 2 tbsp olive oil; 275g basmati rice; 400g Brussels sprouts, roughly shredded; 700ml hot chicken stock (made with 1 stock pot or cube) - use gluten free stock if required; 1 x 600g salmon side; juice of ½ orange; 1 tsp ground cumin; 1 tsp ground coriander; 2 tsp dried oregano; 1 tsp smoked paprika; 1 tbsp pomegranate molasses; 1 tbsp clear honey; pinch of chilli flakes; a squeeze of orange juice; 50g pomegranate seeds; 25g pistachios, roughly chopped; handful of fresh dill, roughly chopped