Cook the chorizo in a large frying pan over a medium heat for 3–4 minutes, turning once, until crisp. Remove from the heat and stir in the butter beans, tomatoes and red onion.
Whisk the oil and vinegar together in a small bowl and season to taste. Transfer the chorizo mixture to a serving dish, pour over the dressing and toss well. Sprinkle with the parsley and serve immediately with crusty bread