Step 1

In a large bowl, toss together the tomatoes, cucumber and 1 tsp salt. In a medium bowl, stir together the onion, vinegar, sherry and 1/4 tsp salt. Let both stand for 10 minutes.

Step 2

Using tongs, lift the onion slices from the vinegar, allowing the excess to drain back into the bowl, and add them to the tomato-cucumber mixture; reserve the vinegar. Add the bell pepper, capers and tuna to the vegetables, and gently toss.

Step 3

To the vinegar, whisk in the oil, 1/2 tsp salt and 1/4 tsp pepper. Stir in the parsley. Pour the dressing over the salad and gently toss. Transfer to a serving dish and top with egg wedges and sliced olives.