Place the diced potatoes in a saucepan with hot water and cook over medium-high heat. It will take about 10 to 12 minutes for the potatoes to cook.
While the potatoes are cooking, soften the guajillo peppers by placing them in a bowl of hot water.
In the meantime, cook the chorizo in a skillet over medium-high heat. It will be ready in about eight minutes.
By this time the potatoes should be ready, so remove them from heat and drain. Next, stir them into the skillet with the chorizo, and keep cooking for three minutes.
Allow enough time for the flavors to blend and the potatoes to get a little more tender. Set aside.
Place guajillo peppers, 1 cup of soaking water, garlic clove, oregano, and peppercorns into a blender. Process until you have a smooth sauce. Strain and place in a bowl.
Heat a griddle and add ½ tablespoon of oil. Place the sliced rolls upside down and brush their tops all over with the Guajillo salsa.
Flip the rolls so the tops get a little warm and crispy. This step will be about a minute per side. Repeat the process with the rest of the rolls, adding oil to the skillet as needed.
To assemble the Pambazo, place some chorizo and potatoes on each toasted roll, then top with the shredded lettuce, cream, and cheese.
Serve with a hot salsa or pickled jalapeños. Enjoy!