Prep the chorizo and refried beans following my recipes, or measure out store-bought ones to use.
If making the guajillo sauce (I recommend it!), place the chiles in a heatproof bowl and pour the boiling water over them. Let soak for 15 minutes until fully softened.
Transfer the chiles and soaking liquid to a blender. Add the garlic, tomato paste, oregano, brown sugar, apple cider vinegar, and salt, then blend until completely smooth. Set aside.
Heat a wide skillet over medium heat. After 90 seconds, when the pan is hot, add the vegan chorizo crumbles and cook, stirring every 45–60 seconds, until heated through and lightly crisped in spots.
Meanwhile, in a saucepan, heat the refried beans for 4-5 minutes over medium heat, stirring regularly, until it is hot throughout. Add a splash of water if your beans are very thick.
Split the rolls lengthwise. Toast cut-side down on a dry skillet set over medium heat, or place on a sheet tray and warm in a 375°F (190°C) oven until lightly crisp on the interior and warmed through.
Spoon the hot chorizo and bean mixture evenly over the bottom half of the rolls. Drizzle with the guajillo sauce, if using. Top with lettuce, tomato slices, red onion, avocado, and optional Fresno chili. Close the sandwiches and serve immediately.