Place the potatoes in a pot of cold salted water. Bring to a boil and cook until tender, about 12–15 minutes, depending on size. Drain well and let the steam escape for 2–3 minutes. Lightly mash the potatoes. They should be broken up and fluffy, but not completely smooth like purée. The potatoes should be fully tender and easy to mash, but still dry enough to hold texture once mixed with the chorizo. Letting the steam escape for a couple of minutes after draining, rather than mashing them straight away, removes surface moisture that would otherwise make the filling wetter than it should be once combined with the chorizo's own rendered fat.

Place the guajillo chiles in a bowl and cover with hot water. Let them soak for 10–15 minutes until softened. Transfer the softened chiles to a blender with the onion, garlic, oregano, cumin, oil, salt, and about 250ml of the soaking water or fresh hot water. Blend until completely smooth. Add a little more water if needed to help it blend. Strain the sauce through a fine sieve if you want a smoother finish, then taste and adjust the salt. The sauce should be smooth, vivid red, and fluid enough to coat the bread evenly without being watery. It should stain the bread easily rather than sit on the surface in a thick paste. This sauce's consistency is a genuine balance point worth checking carefully before moving on — thick enough to actually cling and colour the bread, but loose enough to coat evenly rather than sitting as a heavy, uneven paste.

Place a skillet over medium heat. Add the chorizo and cook, breaking it up with a spoon, until fully cooked, fragrant, and lightly crisp in spots, about 8–10 minutes. If the chorizo is very lean and sticks, add a little oil. Add the mashed potatoes to the skillet and fold everything together until evenly combined. Cook for another 2–3 minutes so the flavors come together. Taste and adjust with salt and black pepper if needed. The filling should be cohesive and well mixed, with the chorizo fat lightly coating the potatoes. It should not be wet or loose. Folding the potatoes directly into the rendered chorizo fat, rather than combining them separately, is what lets that fat's flavour distribute evenly through the whole filling rather than pooling on its own.

Slice the pambazo or telera rolls horizontally, leaving a hinge if you prefer. Working one roll at a time, dip or brush the outside of each roll generously with the guajillo sauce. Coat the top, bottom, and sides so the bread turns a vivid red-orange. Do not soak the interior crumb heavily; the goal is to stain and flavor the exterior without making the roll collapse. If the sauce is too thick, the bread will not coat evenly; if too thin, the bread can become soggy. Adjust the sauce consistency before dipping the rolls. Keeping the coating focused on the exterior crust, rather than working the sauce deep into the crumb, is what allows the bread to pick up pambazo's signature colour and flavour without compromising the structural integrity the roll needs to hold its filling.

Heat a large skillet or griddle over medium heat and add a thin film of neutral oil. Place the sauce-coated rolls cut-side open first just briefly if you want a little toast inside, then griddle the outside surfaces until the bread is hot, lightly crisp, and stained a deeper red, about 1–2 minutes per side as needed. The bread should be warmed through and lightly crisped on the outside, but still soft enough to bite through. Do not overcook or the rolls can dry out and crack. This brief griddling stage does two things simultaneously — it sets and slightly caramelises the guajillo sauce into the bread's crust, deepening its colour, while also crisping the exterior just enough to give the roll real structure against the warm filling that follows.

Fill each warm roll with a generous portion of the potato-and-chorizo mixture. Top with shredded lettuce, a drizzle of crema, and a generous sprinkle of crumbled queso fresco. Serve immediately while the bread is still warm and lightly crisp, and the filling is hot. Adding the cool crema, lettuce, and cheese only at this final step keeps those fresh components crisp and distinct rather than wilting against the hot filling and freshly griddled bread.