As delicious as stromboli can be, it's the kind of dish that looks more complicated to make than it really is. It is essentially a rolled-up pizza, stuffed with your choice of toppings. One of the best things about stromboli is that you can prepare it the night before, so that all you have to do is pop it in the oven to bake the next day.
Preparing the Dough
Use a prepared pizza dough to make your stromboli, either store-bought or homemade. You'll need to take it out of the refrigerator an hour or so before you start making the stromboli to let it come to room temperature, which will make rolling it out easier. Flour one of your kitchen counters well and use a rolling pin to flatten the dough out into a rectangle measuring about 11 inches by 14 inches (though it doesn't need to be exact). If the dough is springing back a bit when you try to roll it out, it may still be too cold. Allow it to rest for another 10 minutes or so before trying again.
Adding the Fillings
Stromboli is traditionally filled with a tomato sauce, mozzarella cheese and Italian meats like pepperoni, salami and prosciutto. Generally, you start by layering the ingredients on the dough, just like you would a pizza, starting with the tomato sauce, then the cheese and the meats. Spread the toppings to within a 1/2-inch of the edges of the dough. If traditional stromboli is not your thing, you can add or omit any toppings you prefer, just as you would a pizza. For example, you could skip the tomato sauce and opt for a thin layer of olive oil, replace the meat with vegetables like broccoli or add Parmesan and ricotta cheese instead of mozzarella.
Folding the Stromboli
To fold the stromboli, brush the bare edges of the dough with a little water. There are a number of ways that strombolis can be folded up, depending on which pizzeria or chef you ask. One of the basic rolls is the jelly roll, which simply has you rolling the dough over the fillings, starting from a short side, until you reach the other ends. Tuck the ends under and and seal the seam by pressing over it gently with damp fingertips. Another common way to fold the stromboli is to fold one of the long sides halfway over the fillings, then fold the other half over the first side. Seal the seams and tuck the edges under. For either folding method, cut slits into the bread down to the filling every one to two inches along the length. For a fancier style, the bread is partially cut into thick strips and braided over the filling.
Refrigerating it Overnight
Once your stromboli is assembled, wrap it tightly in plastic wrap and store it in the refrigerator overnight. The next day, when you are ready to cook the stromboli, preheat the oven to about 400 degrees Fahrenheit. Unwrap the stromboli and place it on a large baking sheet. Brush the tops and side of the stromboli with an egg wash, which will give it a nice sheen when baking, but you can skip the egg wash if you prefer. Place it in the oven and bake for roughly 20 to 30 minutes, until the bread is a deep golden brown and you can see the cheese bubbling through the slits in the bread. Let the stromboli cool for about five minutes before slicing and serving.