Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the diced potatoes, season with salt, pepper, and smoked paprika, and cook for 12-15 minutes, stirring occasionally, until crispy and golden brown. Remove from the pan and set aside.
In the same skillet, add the chorizo and cook over medium heat, breaking it apart with a spoon. Cook for about 6-8 minutes, until browned and cooked through. Remove from heat and set aside.
In a separate pan, heat 1 tablespoon of olive oil over medium-low heat. Pour in the beaten eggs and milk (if using). Gently scramble the eggs until just set, then remove from heat.
Warm the tortillas in a dry skillet or directly over an open flame for about 10-15 seconds per side, until soft and slightly charred.
Assemble the tacos by layering potatoes, chorizo, and scrambled eggs in each tortilla. Top with shredded cheese, diced red onion, chopped cilantro, and avocado slices.
Serve immediately with salsa or hot sauce on the side.