Cook chorizo and onions together in until chorizo is browned and cooked through. Add in refried beans. Mix well. Mix in pepper jack cheese and cook until cheese melts. Remove from heat.
Heat a thin layer of oil in a skillet over medium heat. Cook tortillas one at a time until they are soft and pliable, about 30 seconds per side.
Place a heaping tablespoon of the filling in the center of each corn tortilla and roll up. Place the tortillas, seam side down, on a baking sheet. Repeat with remaining ingredients.
Bake taquitos in preheated oven for 10 - 15 minutes or until tortillas are crisp. Remove from oven, top with shredded lettuce, shredded cheese, sour cream and guacamole.