Mustard salmon with celeriac mash

Name: Mustard salmon with celeriac mash
Prep time: 15 min
Cook time: 20 min
Total time: 35 min
Yield: 2 servings
Cuisine: European
Ingredients: 2 Baking potatoes; 1 pinch of Black pepper; ½ Celeriac; 1 tbsp of Dry dill; 1 pinch of Fine sea salt; ½ Orange; 2 Salmon fillet; 1 glass of Semi skimmed milk; 2 slices of Unsalted butter; 2 tbsp of Wholegrain mustard