Boil the potatoes in plenty of water with a little coarse salt. When they're soft, peel and dice them into small cubes. Set aside.

Remove the casing from the longaniza sausage and cook it in a skillet without oil until browned. Set aside.

For the adobo, remove the seeds and veins from the guajillo chiles. Sauté them in oil over low heat so they don't burn. Sauté the onion slice and garlic as well, then soak everything in water to soften.

Blend the chiles, onion, and garlic with a little water, then strain the mixture. Add a bit more water to rinse out the blender, season with a little black pepper, and mix well. The adobo should be thick.

Fry the potatoes with a little fine salt (to taste) until golden. Add the longaniza, mix well, and set aside.

To assemble the pambazos, slice the bolillo roll on one side only and brush the cut side with adobo. Toast or fry the roll in a skillet with a little oil. Flip it and brush with more adobo so the bread is well coated. When golden, fill with the potato and longaniza mixture, add sour cream and lettuce, and enjoy.

Note: I filled the bread before toasting and cut it on one side only, but the filling fell out when I flipped it. To avoid this, you can fill the bread after toasting.