Easy made tuna or salmon pie for a picnic (or as a main dish with a salad)
Mix a tuna or salmon can (can be done with previously cooked fresh fish but it would be a shame to use fresh fish this way IMO) with crème fraîche or sour cream (not half and half, it'd be too watery), add salt and a good amount of pepper. Line a tart pan with pie crust, spread Dijon mustard so you have a thin layer of it, pour the mixture, sprinkle with grated cheese and bake at medium heat for 25/30min