How to make
Soak the beans overnight in water to swell. The next day, boil them with a little salt and 1 tablespoon olive oil. Soak the smoked mackerel in water for a few hours, then remove the skin and bones.
Tear the fillet into pieces. Braise the chopped onions and garlic until caramelized in a little hot oil. Combine them in a large bowl with the mackerel and beans, season with salt and pepper and pour on plenty of lemon juice, olive oil and vinegar.
Serve the salad in bowls, decorated with sprigs of parsley.