In a bowl, coarsely crush the sardines with a fork. Stir in the mashed potatoes, egg and bread crumbs. Add the sardine oil (see note). Season with salt and pepper.
Shape each croquette using 1 tbsp of the sardine mixture to obtain 2 dozen. Slightly flatten each croquette.
In a large non-stick skillet over medium-high heat, brown the croquettes in the oil for 2 to 3 minutes on each side. Drain on paper towels. Let cool.
In a bowl, combine the vinegar and oil. Add the shallot, parsley, beans and tomato confit. Adjust the seasoning.
Serve the salad topped with the croquettes.
Canned sardines come packed in oil or water. If packed in oil, add the oil directly to the croquette mixture. If packed in water, drain the sardines and add 1 tbsp (15 ml) of olive oil to the croquette mixture.