The sauce is the soul of Francesinha. Although the recipe differs from restaurant to restaurant and is a closely guarded secret, it should always contain tomatoes, beer, brandy (or wine), and spicy elements (often piri-piri). The sauce should be thick and velvety.
This sandwich is extremely rich, and it is therefore often recommended to be served with an egg on top (optional) and a mound of french fries.
Instructions
Step 1: Preparing the Sauce
Sauté the onion in a little oil. Add the bay leaf, tomato paste, beef stock, beer, brandy/Port, and piri-piri. Bring to a boil and simmer for about 20 minutes.
Strain the sauce or blend it with an immersion blender until completely smooth. Thicken with cornstarch and boil briefly. Keep it hot and liquid.
Step 2: Preparing and Searing the Meat
Pan-fry all sausages (linguiça, salami) and the fresh steak. Slice the seared meat and sausages into thinner pieces.
Step 3: Assembling the Sandwich
Lightly toast 4 slices of sandwich bread.
Assemble the sandwich: 1st slice of bread, 2 slices of ham, 3 slices of linguiça, steak, 4 slices of salami, 2nd slice of bread.
Carefully cover the exterior of the entire sandwich (top and sides) with cheese slices (6 slices per sandwich), ensuring the whole sandwich is covered.
Step 4: Baking and Serving
Place the sandwiches on a baking sheet and bake in an oven preheated to 185 °C (365 °F) until the cheese is completely melted and bubbling (about 5-8 minutes).
Meanwhile, you can fry an egg (optional) in a pan.
Transfer the sandwich to a deep plate, place the fried egg on top. Carefully pour the hot sauce over it so that the sandwich is almost submerged. Serve immediately with french fries for dipping.