For 4 people
For 4 people
Start by peeling the onions then cut them into very thin slices, then put them in a colander and sprinkle them with coarse salt.
Mix and let stand.
Meanwhile, rinse and pat dry the tuna fillet. Then cut it into pieces. Divide them among four plates and garnish with olives.
Rinse the onions, drain, pat dry, and divide them among the plates. Sprinkle the fish with fleur de sel and drizzle with olive oil.
Serve.