Wash all vegetables thoroughly under cold water. Dice the tomatoes into uniform pieces, roughly 1/2-inch in size. Remove excess seeds if tomatoes are particularly juicy to prevent the salad from becoming watery.

Cut cucumbers into similar-sized pieces as the tomatoes. Leave the skin on for extra nutrition and texture, but peel if you prefer a milder flavor.

Slice the red onion as thinly as possible using a sharp knife or mandoline. If you find raw onions too strong, soak the slices in ice water for 10 minutes, then drain and pat dry.

Dice the bell pepper into small pieces and roughly chop the fresh herbs. The parsley should be chopped fine enough to distribute evenly, while mint leaves can be slightly larger.

Whisk together olive oil, lemon juice, salt, and pepper in a small bowl. Taste and adjust seasoning as needed.

Gently toss all vegetables with the dressing in a large bowl. Add crumbled feta cheese last to prevent it from breaking down too much. Let the salad rest for 5 minutes to allow flavors to meld before serving.