Campfire instructions: Make sure the fire is not blazing but have died down and you have a good amount of coals for cooking.
If using an oven, preheat to 200C/400F
Mix the sour cream, milk,mayonnaise and whole grain mustard. Set aside. Wash the potatoes, peel the sweet potatoes if using and slice them into thin ¼ inch slices.
Prepare the aluminum foil by cutting it into 8 sheets that are large enough to wrap slices of potato and salmon, then double layer them. On top of a double layer of foil arrange sliced potatoes overlapping them slightly, season with salt, then pour 4 tbsp of the sour cream mixture all over each potato, fold the side of the foil forming a packet. If using green beans, add them at the same time as potatoes diving them equally between 4 packets. Place on top of the burning coals and cook 20 minutes for sweet potatoes and 25 for regular potatoes. Or bake in the preheated to 200C/400F oven for the same amount of time.
Take them out and carefully open them up, top each packet with a piece of salmon fillet, season with salt and a drizzling of the remaining sour cream mixture. Use tongs to avoid burning your fingers. Fold loosely and put back in the fire/oven for 10 minutes longer. Serve with lemon and dill.