These are easy and satisfying tacos for any time of day, including breakfast. If you can’t find Mexican chorizo, which is fresh and uncured, substitute cured Spanish chorizo, but you’ll need to finely chop it and sauté it in a little oil.
Make the guacamole
Combine half of the onion and half of the cilantro on a cutting board (or in a molcajete, or mortar, if you have one) along with the chile and salt. Mince together with a large knife and mash with the side of the knife to create a paste (or mash with the pestle). Transfer to a bowl. Score the avocado, twist the halves apart, and scrape the flesh out of its skin with a large spoon into the bowl. Add the remaining onion and cilantro and stir together with a fork.
Peel the potatoes and cut them into 1⁄2-inch dice. Cook in a saucepan of boiling salted water until they are just cooked through and still hold their shape, about 5 minutes. Drain.
Remove the casings from the chorizo and crumble (Mexican) or finely chop (Spanish) the meat. Cook the chorizo in a large skillet (add a tsp. of oil if using Spanish chorizo) over medium heat, stirring, for 5 minutes. Add the potato and oregano and cook, stirring, for 5 minutes. Season with salt to taste.
Make tacos with the tortillas, guacamole, and queso fresco, if using.
Photo: Romulo Yanes