Remove the 3 lb carne de res salada con paquete de especias incluido from its packaging and rinse it well under cold water. This removes excess surface brine and helps control the saltiness of the final dish. Pat dry with paper towels.

Place the 3 lb carne de res salada con paquete de especias incluido fat-side up in a large Dutch Oven. Add the quartered 1 cebolla amarilla cortada en cuartos, smashed 4 dientes de ajo aplastados, 2 tbsp granos de pimienta negra enteros, 2 hojas de laurel enteras, 1 tbsp azúcar moreno, and the included spice packet. Pour in the 1 bottle cerveza stout como Guinness (if using) and enough 6 cups agua o la suficiente para cubrir la carne de res salada por 1 pulgada to cover the 3 lb carne de res salada con paquete de especias incluido by about 1 inch.

Bring the Pot to a boil over high heat, then immediately reduce the heat to low. Skim off any foam that rises to the surface during the first 10 minutes. Cover tightly and simmer gently — the liquid should barely bubble. Cook for about 2.5 to 3 hours, or until the 3 lb carne de res salada con paquete de especias incluido is very tender when pierced with a fork. A 3 lb carne de res salada con paquete de especias incluido typically takes about 50 minutes per pound.

Once the 3 lb carne de res salada con paquete de especias incluido is tender, carefully transfer it to a Cutting Board and tent loosely with Aluminum Foil to rest. Do not discard the cooking liquid — this is your broth for cooking the vegetables.

Bring the broth back to a boil over medium-high heat. Add the 1 ½ lb papas baby cortadas por la mitad si son grandes and 4 zanahorias grandes enteras peladas, cortadas en trozos de 2 pulgadas. Cook for 10 minutes.

Add the 1 repollo verde entero núcleo removido, cortado en 6 cuñas wedges to the Pot, nestling them into the broth. Cook for another 15 minutes, or until the 1 repollo verde entero núcleo removido, cortado en 6 cuñas is tender but not mushy and the 1 ½ lb papas baby cortadas por la mitad si son grandes are fork-tender.

While the vegetables finish, slice the 3 lb carne de res salada con paquete de especias incluido against the grain into 1/4-inch slices. Slicing against the grain is essential — it shortens the muscle fibers and makes the meat tender rather than stringy.

Use a Slotted Spoon to transfer the vegetables to a large serving platter. Dot with 4 tbsp mantequilla sin sal para terminar los vegetales if desired and season lightly with 2 tbsp granos de pimienta negra enteros (taste before adding salt — the broth is already quite salty). Arrange the sliced 3 lb carne de res salada con paquete de especias incluido alongside the vegetables, ladle some of the hot broth over everything, and garnish with fresh 2 tbsp perejil fresco de hoja plana picado aproximadamente. Serve with 1 jar mostaza de grano entero para servir al lado on the side.