Heat oil in a large, heavy skillet (preferably cast-iron) over medium heat. Working in batches, add chorizo and cook, stirring occasionally, until lightly browned in places, 3 to 4 minutes. Transfer chorizo to a serving dish.
Add onion, chiles, and 1 teaspoon salt to skillet, and raise heat to medium-high. Saute, stirring occasionally, until onions are translucent, about 5 minutes. Add tequila, bring to a boil, and cook until tequila is mostly absorbed by vegetables, about 30 seconds.
Reduce heat to low, gradually stir in cheese, and cook, stirring constantly, just until cheese is melted, 5 to 7 minutes. Transfer to a fondue pot, and serve with chips and chorizo.