Prepare the dressing. Add the olive oil, vinegar, parsley, salt, pepper, and the juice of ½ of a lemon to a screw top jar. Seal and vigorously shake until emulsified. You can also just whisk this together in a bowl. Add more lemon juice to taste if needed.
Prepare your vegetables, fruit and herbs. Slice the tomatoes and cucumbers in half and use a metal spoon to scrape out the seeds. Then finely dice.
Mix and dress. In a large serving bowl, mix the finely diced tomatoes, cucumbers, peppers, apple, and mint. Stir in the dressing.
Add onion to taste. Mix in half the onion, taste, and add more onion to your liking. I usually end up using all of it but it really depends on personal taste. Remember that its tanginess will be tamed by the lemon juice and olive oil in the dressing.
Finish the salad. Before enjoying, transfer the salad to a large serving bowl and top it with 6 wedges of hard boiled eggs, olives and tuna. You can use as much as you like of any of these depending on your taste preference and hunger level. Serve the remaining egg quarters on the side.
Serve. Serve with a side of fresh crusty baguette slices, which can even be used as a vessel instead of the fork.