Heat oil in a large frying pan over medium heat. Add chopped onion and bell pepper, stir, cooking until fragrant and slightly softened, about 3 minutes
If chorizo is in a casing, slice casing from end to end of the chorizo. Remove chorizo from casing and place in the hot pan. Cook, stirring and breaking up the meat for about 10 minutes until meat is cooked through. Transfer chorizo to a serving bowl, draining any excess oil or grease that has accumulated while cooking
While chorizo is cooking, warm tortillas according to the instructions on their package
Next, assemble the tacos. Spoon several spoonfuls of chorizo mixture into each taco. Garnish as desired and serve.