Hot mustard tuna with herby couscous

Ingredients

• 1 red onion
  
  , halved and finely sliced
• zest and juice 1 lemon
  
  , plus wedges to serve
• 1 tbsp olive oil
  
  , plus extra for brushing
• 400ml hot vegetable stock
• 250g couscous
  
• 4 tuna steak, about 140g/5oz each
• 2 tsp English mustard powder
• bunch flat-leaf parsley, roughly chopped
• 2 tbsp capers

  Method

  1. Put the onion, lemon zest, juice and 1 tbsp oil into a small bowl, add salt and pepper to taste, then leave to soak for 5 mins until the onion has softened a little. Pour the hot stock over the couscous in a large bowl, cover with cling film and leave for 10 mins until the stock has been absorbed.
  2. Season the tuna steaks, brush with oil, then pat the mustard powder over both sides. Once the couscous is ready, add the parsley and capers to the onions, stir well, then mix into the couscous with a fork. Heat a griddle pan and sear the tuna for 1 min on each side until medium-rare. Serve the tuna with the couscous and lemon wedges on the side.
  3. Source: bbcgoodfood.com