Tuna Mornay is a casserole dish containing tuna, pasta and a Mornay sauce, a white sauce to which cheese and spices have been added. Vegetables and pasta are prepared and added to the sauce along with the tuna. The ingredients are then poured into an oven dish for baking.
There are a number of variations for this seafood dish. Most recipes for Tuna Mornay begin with the preparation of the white sauce. Flour and butter are blended and heated in a pan to create a roux. The roux is cooked just until it begins to have a slightly nutty smell; it is not allowed to brown. Milk is added to the roux and the mixture is brought to a boil.
Grated cheese, vegetables and cooked pasta are mixed into the sauce and heated. These ingredients are then transferred to a casserole dish and the top is covered with shredded cheese, bread crumbs or a mixture of the two. Melted butter also is sometimes drizzled on the top.
This is a dish that can be adapted for whatever type of fish or meat one has available, and leftover meats are often used. Tuna Mornay also can be made with different vegetables, such as mushrooms, carrots or zucchini. Any fresh vegetables should be sautéed or boiled before adding to the sauce and baking.
Other types of shellfish, such as lobster, shrimp or scallops, can be prepared as a Mornay casserole. Cod and salmon also are substitutes for tuna. Chicken, turkey and red meats also can be prepared in this way, though some adjustments to the preparation of the roux may be necessary.
Tuna Mornay need not be served with pasta. It can be made with rice, couscous or other whole grains. After the filling is prepared, it can be served over a bed of vegetables, noodles or rice instead of being baked.
Subtle changes can be made to the basic recipe through the prudent and sparing use of herbs such as mustard, white pepper and sea salt. The roux can be cooked further to yield a darker and more fully flavored base, which is often more appropriate for meats and stronger flavored fish such as salmon. The addition of cherry tomatoes, green beans and yellow zucchini creates a dish that is pleasing to the eye and the palate. Wine, cream and eggs can further add variety and new flavors to this versatile dish.