Put the judión beans into a large bowl (remember that they will expand) and cover with plenty of hot water. Leave to soak overnight.
The next day, drain the judiones and put into a pan with fresh cold water, the bay leaves and the onion. Place on a medium heat and bring to the boil, then reduce the heat and cook until nice and soft. Drain.
In a large bowl, whisk together the olive oil, vinegar, salt and pepper to make a dressing, then add the fennel, dill and drained beans and mix together. Spoon on to small plates, and top with the salmon.