Salmon with new potato & watercress salad

Name: Salmon with new potato & watercress salad
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: British
Ingredients: 1 banana shallot halved – one half thinly sliced, the other finely chopped; 220g pack salmon trout or salmon fillets skinned; 1 tbsp chopped dill plus 2 sprigs; 1 ½ tbsp white wine vinegar; 250g new potatoes sliced; 140g trimmed green beans halved; 1 tbsp extra virgin rapeseed oil; 1 tsp wholegrain mustard; small handful watercress finely chopped