Step 1: Generously season the secreto with salt and ground pepper and dust with paprika.
Step 2: Lay the secreto directly on the grill grate. Sear for about 2 minutes per side. Do not overcook. Transfer the meat to a cutting board and let rest for 1 to 2 minutes. Slice thinly on a diagonal against the grain. Transfer the meat and its juices to a platter or plates, then drizzle lightly with olive oil. Squeeze fresh lemon juice on top.
Step 3: Serve, if desired, with Romesco sauce and grilled calçots.