In a paella pan or a large, wide skillet, heat 2 tablespoons of olive oil. Add the cuttlefish or squid and sauté for a few minutes. Remove and set aside. Add the shrimp or prawns and cook for a minute on each side until they change color. Remove and set aside.
Add the remaining 2 tablespoons of olive oil to the pan. Add the finely chopped onion and garlic and sauté until soft. Stir in the grated tomato and sweet paprika and cook until a thick sofrito is formed, about 5-7 minutes.
Add the short noodles to the pan with the sofrito and stir constantly for 2-3 minutes until they are toasted and golden brown. This step is crucial for flavor and texture.
Add the cooked cuttlefish/squid back to the pan. Pour in the hot fish stock and the saffron threads. Bring to a boil, then reduce the heat to a steady simmer. Do not stir the noodles from this point on.
Cook for about 10-15 minutes, or according to the noodle package instructions, until the noodles are standing upright and the liquid has been absorbed. You can place the shrimp/prawns back on top for the last few minutes of cooking to heat them through.
Remove from heat and let the fideuà rest for 5 minutes, covered. Serve immediately, directly from the pan, with a generous dollop of alioli sauce and lemon wedges on the side.