Smoked mackerel, orange & couscous salad - Good Food Middle East

Ingredients

• 200g couscous - use wholemeal if you can get it
• 3 oranges, 2 peeled and thinly sliced, 1 juiced
• 3 tbsp red wine vinegar
• 1 tsp sugar
• 3 tbsp olive oil
• 1 red onion, finely chopped
• 100g bag watercress, roughly chopped
• 240g pack peppered mackerel fillets, flaked into large chunks