Remove the outer leaves of the iceberg lettuce, rinse thoroughly under cold water, and pat dry. Cut into quarters, remove the core, and chop into bite-sized pieces. Place in a large salad bowl.
Wash cherry tomatoes and slice them in half. Add to the bowl with the lettuce.
Peel the cucumber if desired. Slice it lengthwise, then cut into half-moon shapes about 1/4 inch thick. Add to the salad bowl.
Thinly slice the red onion into half-moons. If you find raw onion too strong, soak the slices in ice water for 5 minutes, then drain and pat dry. Add to the salad.
Crumble the feta cheese over the vegetables, reserving a little for garnish if desired.
In a small bowl or jar, whisk together the olive oil, fresh lemon juice, salt, and pepper until emulsified. Taste and adjust seasoning if needed.
Just before serving, drizzle the dressing over the salad and toss gently to coat all ingredients evenly.
Finish with any optional toppings and the reserved feta cheese. Serve immediately.
