Start by marinating the beef slices in a mixture of lemon juice, soy sauce, and black pepper for 30 minutes in the refrigerator (Ibabad ang karne sa pinaghalong katas ng dayap, toyo, at paminta ng 30 minuto sa refrigerator). Reserve the marinade for later use.
While the beef marinates, cook bacon until just soft but not crispy (Lutuin ang bacon hanggang lumambot pero hindi malutong). Prepare the filling ingredients: cut carrots into strips, slice hotdogs lengthwise, cut cheese into strips, and have the hard-boiled egg halves and pickles ready.
Lay the marinated beef flat on a clean surface. Layer in this order: bacon, carrot strips, hotdog slices, pickle strips, cheese strips, and egg halves (Ilatag ang mga sangkap sa ibabaw ng karne sa ganitong pagkakasunod-sunod). Roll the beef tightly like a jelly roll. Secure with kitchen twine every inch (Talian ng pantali bawat isang pulgada). Coat the entire roll with flour.
Heat oil in a heavy-bottomed pan over medium-high heat (190°C/375°F). Brown the beef roll on all sides, about 2-3 minutes per side (Iprito ang morcon sa lahat ng gilid hanggang maging golden brown). Remove from pan and set aside.
Reduce heat to medium (165°C/330°F). In the same pan, sauté onions until soft (Igisa ang sibuyas hanggang lumambot). Add garlic and cook for 30 seconds (Idagdag ang bawang at igisa). Add the reserved marinade, tomato sauce, beef broth, and bay leaf. Stir in liver spread until smooth.
Return beef roll to the pan. Reduce heat to low (140°C/285°F). Cover and cook for 1 hour and 20 minutes (Pakuluan ng mahina ng 1 oras at 20 minuto), turning the roll every 20 minutes (Baliktarin ang morcon bawat 20 minuto). Test tenderness with a fork - if not yet tender, cook for an additional 15 minutes.
Let the morcon rest for 10 minutes before removing the strings (Palamigin ng 10 minuto bago tanggalin ang tali). Slice into 1-inch rounds and serve hot with the sauce poured over (Hiwahin ng 1 pulgada at ihain na mainit kasama ang sarsa).
When reheating, ensure internal temperature reaches 165°F/74°C (Kapag iinitin, siguraduhing umabot sa 165°F/74°C ang init sa loob ng karne).