Pat the 2 ½ lb hombro de cordero sin hueso o carne para estofado pieces thoroughly dry with paper towels. Season all over with the 1 ½ tsp sal kosher más cantidad and ½ tsp pimienta negra molida fresca. Drying the meat is essential — wet lamb will steam instead of sear.

Heat the olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat until shimmering. Working in batches (don't crowd the pan), sear the 2 ½ lb hombro de cordero sin hueso o carne para estofado pieces for 3–4 minutes per side until deeply browned. Transfer the browned lamb to a plate and set aside.

Reduce the heat to medium. Add the 1 cebolla grande and 2 tallos de apio to the same pot (with the drippings) and cook, stirring occasionally, for 4–5 minutes until softened and lightly golden.

Add the 3 dientes de ajo and 2 tbsp pasta de tomate and stir for 1 minute until fragrant and the paste turns a slightly darker, brick-red color.

Sprinkle the 2 tbsp harina multiusos para espesar evenly over the onion mixture and stir well to coat, cooking for 1 minute.

Pour in the lamb stock and 1 cup agua para cubrir, scraping up any browned bits from the bottom of the pot with a wooden spoon — those bits are pure flavor. Return the browned 2 ½ lb hombro de cordero sin hueso o carne para estofado (along with any resting juices) to the pot.

Add the 2 hojas de laurel enteras, 4 ramitas de tomillo fresco sprigs, and 1 ramita de romero fresco (if using). Bring the stew to a boil over high heat, then reduce the heat to low. Cover with a lid slightly ajar and simmer gently for 45 minutes.

Add the 3 papas medianas Yukon Gold peladas y, 3 zanahorias medianas peladas y, and 1 chirivía mediana pelada y (if using) to the pot. Stir to submerge them in the broth, adding a splash more 1 cup agua para cubrir if needed to just cover. Continue to simmer, partially covered, for another 35–40 minutes, until the 2 ½ lb hombro de cordero sin hueso o carne para estofado is fall-apart tender and the vegetables are completely cooked through.

Remove and discard the 2 hojas de laurel enteras, 4 ramitas de tomillo fresco sprigs, and 1 ramita de romero fresco sprig. Taste the broth and adjust seasoning with 1 ½ tsp sal kosher más cantidad and ½ tsp pimienta negra molida fresca as needed. If you'd like a thicker stew, use the back of a spoon to lightly mash a few potato chunks against the side of the pot and stir them in.

Ladle into deep bowls, garnish generously with fresh perejil fresco de hoja plana picado groseramente, and serve with crusty soda bread or Irish brown bread for dipping.